Man could have literally just broken up with her, or been upfront about the fact he didn't saw their relationship as serious or exclusive when Louise clearly thought otherwise.
Yes, but then he'd have to face the same drama and complaints over the breakup he ultimately experienced, while giving up on sex. I hope no one is harboring illusions breakup with Louise would be a clean affair. It's easy to see why from his point of view it was preferable to keep stalling.
(am not saying it was a good thing to do, but simply that with this kind of attitude the ultimate outcome didn't serve as any sort of a lesson -- the drama was going to happen sooner or later, so not having to face it sooner and having some sex for a longer while was a "win", if anything)
Jeremy kept his mouth shut because he was already able to get some with Louise and knew that the moment she realized what he was about that she would dump his ass (at least with how the characters were at the start of the game).
Precisely. No fucks were given and no lessons were learnt.
You could argue Jeremy thinks he only messed up by getting caught rather than cheating in the first place, but I don't think he is on that level of sociopathy yet, just a bit shameless and trying to hide under the excuse that it was just a misunderstanding between him and Louise that he didn't correct in time.
I don't think it's sociopathy per se, just a very typical level of selfishness you'll see in many YAs. Heck, in people in general. It could be argued Lena, Ivy, Mike (and even Ian) can display the same sort of self-centeredness where personal pleasure counts first and foremost, and no serious thoughts are given to how other people affected by one's actions might feel about it. At least not to the point of feeling some actual remorse and learning anything from it.