@veeeka I think her goal might genuinely be to get a friend. Remember that she started out as the class trash that almost everyone would treat badly. But she had kept going along because "at least it's not everybody who does it". Then one day the last person she cared about, one particular boy, joined in with the chorus of bad voices and she snapped.
As for jumping - maybe she had planned out some parts of it before, maybe it was all a spur of the moment thing, maybe it was a genuine suicide attempt (and pointing him out just because he was the "final straw" that broke her back).
But then she didn't die, which kind of made her feel immortal. And she had grabbed the attention of the class, so suddenly her actions did have meaning. (Also her jump out of the window had granted her a temporary immunity towards maltreatment, since nobody wants to kick the angry badger while everyone is still looking.)
Carrying on from that, she now has agency and she also got a boyfriend (mostly from guilting it into him but also by being rebound girl), so to get a proper "springtime of youth", of course she also needs a BFF (best female friend). And since her drama manipulations have worked so well lately, she'll carry on the same way and see if it works anew.