Not also Jill's characterization, but MC's too. He's been a kind, supportive guy, and that's why Jill likes him so much. He has promised a friend in need to be there for her and then Jill come out of the blue and invites him to a surprise date. All while being in a emotional conflict thanks to Tybalt, so I can even understand she takes this date like a turning point ("does MC really worth it...?") Problem is the in-game MC is not aware of this crucial detail. We as players know what's happening and that kind of info asymmetry is something I never liked in games, because it's forcing me to make a decision in the name of a character that doesn't have the same inputs than me, so immersion is broken. I'm choosing like "me, the external player", not like "me, my in-game MC". And I hate that.
Well, what I say is that the man Jill has started to love would probably go to confort a friend who he knows that needs him (and who he has promised to help) instead of having a selfish, nice date with a girl that, in that moment, he can't possibly know that also needs him to step forward for her (of course, she never tell him that, and he never comes up with a rain check). And by making that most logical choice according to his previous behaviour he's closing the door to the girl that, till this point, was more aligned with his character. Emotional manipulation and lack of a proper communication, that's the only way DPC knows to do things, time after time.