Best Coast returned with their third album, California Nights, back in May, but just one month later Bethany Cosentino decided that she'd had enough.

Fed up of batting questions about her apparently "bummed out" stage demeanour during recent live performances, the singer delivered an open letter riposte on her Twitter account explaining that actually, she was really fine. "When I started Best Coast I was 23 years old. I was awkward, I was confused, I had no idea how to carry myself on stage and off. I am now a few months away from turning 29 and I can honestly say that I feel the most confident I have ever felt in my entire life. Just because I come out on stage and I don't say as much as I used to or I don't have as much silly banter in between songs does NOT mean I'm in a bad mood. I'm just a bit of a different person now and I would appreciate people to respect that and be happy for me and the fact that I've grown up into the woman I am today." Perhaps even more germane, read the next line: "If you yell something at me about cats and I don't respond - I'm not pissed, I just simply don't feel like talking about cats in that current moment!"

Since making the breakthrough with the revered Crazy for You in 2010, felines have assumed a totemic significance in the Best Coast narrative. Cosentino's own cat, Snacks, appeared on the band's first album cover and can lay claim to a Twitter account boasting over 10,000 followers. Along with weed and episodes of Seinfeld, they serve as a shared interest and point of entry for fans and journalists alike. The day before I conduct this interview, I ask Cosentino's PA if there are any topics I should avoid bringing up, to which I'm told: "Maybe just focus on the new album first before you talk about cats." Cosentino's status as an ailurophile is clear, but having to deal with the same heckles and facile interview questions nearly every other day for the last 5 years? You can see why she might sometimes not feel like talking.

"See, the thing for me is that so much of my art is not calculated. The way I write is very stream of consciousness and I almost use writing as a way of journaling. So, when I write things they're not premeditated."

Two of the most endearing aspects of Cosentino have always been her accessibility and relatability. Recently she was christened by The Fader as "indie's first social media celeb" and it's that online presence which has been fundamental in garnering her one of the most ardent fandoms in all of indie rock. As her career has progressed and personality matured, some have found it difficult to move on from Bethany the girl and realise Bethany the woman, with the aforementioned cat comments only microcosmic of the issue. As one review of the bands 2010 sophomore album, The Only Place, put it: "Bethany Cosentino is no longer the girl next door to lust after. She is a successful pop musician who is shedding away her relatability. The dreamy innocence is gone, replaced with a material dullness, an expensive real world."

Just about everyone from Alex Turner to Tyler, the Creator have come under similar scrutiny from the public's gimlet eye in the past, as if by turning their hand to more expansive themes they're guilty of breaking some kind of implicit pact which rules that they must remain oblivious to the trappings of fame. It's a bit like saying "hey, growing up is okay, but just make sure we can still relate to the way in which you do it." For Cosentino, it's simple: "I'm a human being and I change and I grow. My music is always reflective of what I am feeling emotionally at the time. I think there's a lot of subject matter on this record that is similar to what I've written in the past, but I was also conscious of the fact that I wanted to write a handful of songs that were different from anything that's come before. Stuff like insomnia, which I've talked about but never really written about. I also wrote a song called 'Jealousy', which is about this idea that there are people out there that exert a lot of energy to hate things for no reason. I'm guilty of that as well, I definitely judge people prior to knowing them so for me I wanted to say 'OK, this is something you're guilty of and you should stop doing it'. I can't really write a song today that I would have written when I was 23."

Conversely, when California Nights was announced in February, its title alone was enough to have some cynics circling. For every person critical of Cosentino's supposed shedding of self, there are others who claim she's forever locked in a stasis of boys, heartache and the Golden State ideal. "Good grief. This girl sings about California more than Anthony Kiedis," were the words of one online commenter, while Stereogum weighed in on the accusation with a deconstruction on the wider theoretical contention of artist growth. Consentino has never denied the influence of California in her music, but has always maintained that it informs, rather than defines it.

"See, the thing for me is that so much of my art is not calculated. The way I write is very stream of consciousness and I almost use writing as a way of journaling. So, when I write things they're not premeditated. When I named the record California Nights, I didn't think 'Best Coast - California Nights' - here's another California thing. Honestly, it did not even come to my mind. I remember when the song came out a lot of people were like 'oh, this girl writes about California yet again', but the song isn't even about California - it's about a feeling - a feeling a California night evokes. It's also about this idea of transcending yourself in the way that love or the way that the place you live can get you high and take you out of the context of that you're currently in. I do sometimes feel like it's my own fault for the whole thing because I did name my band Best Coast and I and I did name the album California Nights, but sometimes the first question out of a journalists mouth will be 'so... California?' It's always been a theme and inspiration because I was born and raised here, but for me this record is more a coming of age story of a woman who is trying to figure out who she was and what she's went through to get to this point. For example, the song 'Feeling OK' is about reaching a point where you're at this level of contentment where things are good - they're not perfect, but then nothing in life is. Now when I do interviews and people are like 'so, this record, it's about California?', I just roll my eyes and am like 'yeah...' because if that's the way people perceive it then I don't think they're reading into it the way that they should be. When the single came out and people were talking about California, I thought 'what?!' but then they'd be like 'don't call the song and record California Nights then'.

"I'm not trying to make a record that's meant for arenas."

On previous albums, it's been said that Cosentino would hide her voice behind layers of reverb and distortion as an extension of her on-stage anxiety, but on California Nights the instrumentation is as bright as the production is bold. For the band, the record has inadvertently proved useful in helping them feel more at home in some of the bigger spaces that have presented themselves as a concomitant of their ever growing status: "When we toured with Green Day we were playing arenas as a 4-piece, but I remember thinking to myself 'oh my God, this is so scary' because at the time I didn't think we were a band who were ready for that and really, I still don't think we are. If we organically reached that point I'd be into it, but I'm not trying to make a record that's meant for arenas. It helps having a bigger set and record where songs are a bit more accessible to fans coming to see the other band and not necessarily us. The new found confidence the record has given us allows us to play those venues without feeling like we don't belong in them."

It could be seen as weird that the singer has found such equanimity as audiences have got bigger, but then again, "singer" is the operative word when describing Cosentino, and the addition of Whirr's Joe Bautista on guitar and keys has proved liberating in that regard: "I think that it's really enhanced the live show but it's also fun to have to have a lot more going on on stage. For me, there's a lot less pressure having somebody else play the guitar. I feel like I can take breaks in certain songs and if I mess up I'm like 'oh well, there's another person playing' so it's not as audible, whereas before if I made a mistake every person in the audience could hear it."

The maturity and confidence in the Best Coast sound is reflected in Cosentino's character. Having spent the best part of her 20's growing up in the public glare, she's now reached a stage where she feels she can put that experience to good use. In her early career, she admitted to struggling with online abuse from trolls (a particularly nasty beef with the now defunct Hipster Runoff springs to mind), but long term there's the sense that it's only served to fortify her personality. Recently, she recorded a video for Rookie's "Ask a Grown Woman" series where she advised teenagers on issues such as anxiety and family problems, and for several years has been one of the biggest supporters of the Planned Parenthood organization. When a seedy review of a Best Coast live show appeared last week ("she looked sexier and badder [sic] than any rock star I've seen in years"), Cosentino called the writer out publically. As was evidenced a week prior when Lauren Mayberry of CHVRCHES slammed a heckler at a live show and the subsequent footage appeared online, the internet can be an unforgiving arena for a woman speaking out, but Consentino feels risking such opprobrium is a necessary occupational hazard:

"If somebody is making you uncomfortable or says something about the way you look be it positive or negative - if it doesn't belong there - then of course you should speak up against it and say this isn't ok."

"I think you're always going to have backlash, it doesn't matter what you stand up for or whatever you're doing, but getting backlash for standing up for yourself and saying that you felt that a person's review was less about music and more about being a female and what you look like? I remember reading stuff that Lauren had written months ago and thinking 'this is awesome that she's doing this'. It happens to every single woman I know, and not just women who play music. I think if you are afraid of backlash and that's why you keep your mouth shut, well... I just think you have to remember that you're a role model for people out there. For me, I have a lot of really young fans - a lot of whom are young female fans - and I want to set an example for these girls and say 'hey, if somebody is making you uncomfortable or says something about the way you look be it positive or negative - if it doesn't belong there - then of course you should speak up against it and say this isn't ok.' She also confirmed that Mayberry had reached out to her after the incident. "I really respect what Lauren did. I started following her on social media and she wrote me a little note and gave me a thumbs up for what I did. I think we live in a generation now where, because it's the internet age, a lot of dumb people are given voices, but so are a lot of nice, powerful people who can make an impact, so I think it's important to use it because in the past you might not have been given the chance to help people out or educate them on things. I try to use my social media/Twitter for both silly things such as television shows I'm watching or food that I'm eating, but also to educate people and stand up for myself."

With a clothing line already under her belt as well as several co-writing credits, Cosentino's career doesn't begin and end with Best Coast. For the moment at least, however, she's quite happy to take things as they come. "I do love playing with Best Coast, but I'd also like to do other things like record something with someone else or friends. I'm not entirely sure what the future holds after this, I just know that I could never go back to a job that doesn't involve being artistic and creative on a daily basis. I'm trying to sort of be in the moment as a person whereas before I was always stressed about either the past or the future."

Whether it's fashion, music or acting, it's apparent that Cosentino has realised herself and won't approach any such challenges with the same trepidation that she might have in the past. But who knows, maybe she'll just be happy spending some time at home with her cats.

California Nights is out now. Check out Best Coast at the following dates:
28 October - Kulturfabrik, Esch Sur Alzette, Luxembourg
29 October - London, Electric Brixton, UK
30 October - Liverpool, The Kazimier for Liverpool Music Week, UK
31 October - Dublin, The Academy, UK
2 November - Luxor, Cologne, Germany
3 November - Bi Nuu, Berlin, Germany
4 November - Bitterzoet, Amsterdam, Netherlands