I've been playing this game for a pretty long time now, with the first playthrough starting as the man-slut. Things were cruising along until around chapter 16 or so and I figured out that the man-slut was untenable as a final ending. I even understand why the developers sort of encouraged the man-slut route because it gave access to a lot more information to the player.
I have been slowly replaying the game as a single romance of Monica. I have done my best to not do anything lewd with anyone else, although it has been hard to so do. For instance, it would be hard to break Jenna out of her shell without encouraging her to know that she is beautiful, and to be more comfortable with her body image.
I only have one issue with the developers. When one of the women that I have no interest in comes on to me, I am really forced to turn her down flat, with no explanation. This usually causes massive degradation of like/love and lust. Not once have I been given the option to say, "I'm sorry, I'm in a relationship already, and it is an exclusive one. You're very beautiful, but I'm already committed to someone else", rather than "Leave me alone, I don't want you". Never had the ability to say anything remotely similar to that, which might mitigate some of the hurt feelings from being turned down.
Has this ever occurred during a playthrough for any of the other women?