I'm confused re the "it's not all about you" comments. Jake was very very clearly joking at the time, yet she's relaying it to the others as if he said it in an angry, nasty way? OK, I get that she has the gut feeling, but why has she turned that incident into something that it wasn't?
Also, she needs to really have a sit down and think things through logically for the future. A relationship isn't about "you think I'm messy and that means you don't love me for me, ergo we're not right for each other." Sheesh, imagine how many couples would actually last if they had to match in every way. Again, I don't think they're suited, but not for those reasons.
I think he's joking with her a lot, and she doesn't really get his sense of humour, she wants a lot of reassurance which he can't be arsed giving her.
I also don't know why the girls are going on about him "not fighting for her ".
She told him over a few days that she felt like things had changed and then said they should go their separate ways. I'm not sure he felt that there was much to fight for by that stage. She'd been miserable for days and was taking every single thing to heart.
In saying that, he clearly wasn't in love with her, so had nothing to fight for.
I also think that he coupled up with her cos he did fancy her, but her character and morals and personality didn't match what he had expected from how she looked (ie insecure, not confident etc), which stopped things in their tracks a bit, but by that time he had to go through the motions a bit.