Im not sure, in the first talk between Jill and Bella, (when Bella mentions that MC is WAY BETTER than tybalt no matter how shit you behave so far lol), Jill didnt really seemed like she even disliked tybalt.I don't know if that's really Jill's fault.We learn from Sage that Tybalt has been saying he and Jill were into eachother for quite a while. We also know that Jill tried to get into contact with Sage at least a couple times in the past but that Sage avoided her about every time.
She probably already found Tybalt annoying to even a dirtbag (I doubt she started ignoring his posts on Rooster when MC came into the picture), but just that Tybalt "upped his game" when Tremolo arrived.
Even if tybalt just "upped his game" afterwards, she was still oblivious to him being a shitbag at this point which is ... well ... questionable.