Respectfully going to have to disagree on that, my friend.
I've seen people say this quite a bit, that's there's an "old Maya" and that she "changed" when Josy arrived, and to an extent that's true, but not as much as people think. The way Maya was before Josy arrived is who she is and who she still is, the difference is that in those first 2 weeks she was simply trying to not think about her problems, both with her relationship and with her Dad, so by repressing these thoughts and by simply trying to enjoy college life, it allowed her to be her more carefree and jovial self. Shortly after that moment with the MC, however, when she's talking to Derek, you see the façade crumble because all that happiness and joyfulness goes away when she's reminded of her problems.
When Josy arrives, it simply brings those problems back to the foreground and she dwells on them to the point where she allows it to negatively affect her demeanour, but that happy, joyful Maya is still in there, she's just being overwhelmed by the issues in her life. Therefore, if these issues that so heavily weigh her down are resolved or can at least be forgotten for a while, you'd see that side of her come back and it can come back when she's still with Josy because Josy doesn't bring her down, Maya's Dad brings both of them down. They're just as good together as they are separately, the problem is simply Maya's Dad.