From what I can tell. MH is "weak and swayed easily by others". She sneaks into mens dorm on school trip to be with MC, but bumps into MC's "friend" instead, friend "persuades" her to bump uglies. I'm pretty sure MC sees this. As MH stumbles through cocks trying to apologize for what she did, she eventually bangs MC. It does feel good, but MC can't reach her "deepest place" so she decides to go full turbo slut.
In the end she's doing prostitution (Or Compensated Dating for weebs). For a split second, she kinda looks frustrated with what her life has become, but cock calls yet again.
Yes, in the extra chapter (black and white pages) she is just having sex as a way to cope with the way her life is now. She isn't happy, sex blows her mind somewhere she doesn't has to worry but once sex ends she feels empty and only the money remains, she quickly moves to her new appointment, she smiles but her eyes are empty.