Be careful overindulging with side chicks even if you aren't yet exclusive with Jill.. If you are on the Jill path and are unironically interested in "romance" then I would not be banging every girl you can on the side. If you truly want what Jill is offering, then you should probably go easy and try not to Genghis your way through B&R. There are other LIs and playthroughs for that, like you and others have mentioned...unless the goal is to see Jill break.
Never believe a girl when she tells you it's OK to see other girls. She'll reserve the right to change her mind after you've been with another girl, and backdate it to before.
Jill spoke all open-mindedly about expecting jealousy:
Jill: "I admit, it's not the best thing to hear for a girl... That there's competition and all."
Jill: "If the guy is worth the time, there's bound to be jealousy involved."
That was until she found out how many girls could identify the mc's erect cock at a glance. When the wave of jealousy went over her, it hit her hard. It was an amusing as fuck scene, but I wouldn't do that shit too often with someone like Jill (assuming once wasn't already too often).
She admits to the MC that she prostitutes herself, but not that she fucks Burke for the free tuition? It makes no sense to me.
We don't know the 100% accurate specifics of the free tuition. All we know is Cammy fucks for money.
mc: "Do you do this a lot, by the way?"
Cammy: "Do what?"
mc: "Have sex for money."
Cammy: "Fuckface... I don't talk about this. It's just something I do, ok?"
mc: "All right. I was just curious."
mc: "Did I upset you?"
Cammy: "Look, it's not something I thought I'd do. I'm not proud of it."
Cammy: "And I don't discuss it, because I don't want it to bite me in the ass later on."
Cammy: "I want it to be discreet."
Cammy: "(Unlike Mona... Fuck...)"
Cammy: "That's why I only agreed to do it through glory holes."
I don't think she's lying. She's just making some money on the side (not full tuition amount probably). But the way we saw Quinn grooming Cammy during the panty-raid scene, I'm sure Quinn hasn't finished nudging her.
That's why DPC will have introduced jealousy in Jill and I wouldn't be surprised if he implements that for all LI's.
I'm not entirely certain the Jill jealousy counter was for anything other than tallying up the count for that scene to play out, although there were only two triggers (Sage's response and Josy's response), and she reacted the same for either or both.
So it's possible this may be a monster growing inside Jill, with each girl she finds out about incrementing the jealousy counter by 1, except if she finds out about Bella, the counter is sure to explode!