Sally's attitude has already been discussed here, the problem is most likely because she takes xanax, which has irritability as a side effect, and we know that she doesn't treat the MC in any special way, the way she treats him, is the same as she treats everyone.
Basically every scene of hers she is angry, including the scenes that don't contain the MC, and we know that her relationship is in a bad moment, probably because she is unbearable.
She must have realized that too, everything indicates that she should start to soften, give the MC more chances (and maybe others too, but we probably won't see renders about others).
I like Sally simply because she is a rarity in this game, she plays hard to get, which makes me want to own her even more, but I imagine that after I get her I will lose interest.