I have already said that it is not credible that the girls in the restaurant, at least them, did not have sex with other men in the course of Badik's story, but it is deliberately left vague so that no player feels his feelings are hurt.
it's true that Burke says he had sex with three female students, but that means very little. he could be lying, we don't know who he's referring to and to be honest we don't even know when that statement refers to, technically that scene could be a flashback.
I get the gist, but it's in game and it's not vague but hidden deliberately but if one goes looking for the details its there. Let me point that out:
EP 1 free roam: Quinn and Riona coming out of toilet, and when we go in toilet, in the glory hole there is a guy in white striped black pants and Burke wears them.
Ep2/3: During lunch time with isabella, Quinn Riona waiting in front of toilet in background, after MC finishes his gf story camila comes out from the same toilet.
The conversation I told you confirm that Sarah and Melanie also fuck on side according to menu.
The Burke scene isn't flashback. Remember how burke sponsors education, why can't he do that for Quinn, Riona and the unknown girl. You are forgetting the most important clue, Quinn setup the Mona-Burke scholarship and lined up for Maya next. So Burke-Quinn have had a deal like this before.