Small mechanics dump:
-hmm... apparently i was right with my assumption millions of years ago: your girl dragging you to the shitter/shower for sex earns you 15 partial hate points with her. Ive noticed this, when my girl asked me to follow her to one of these twice in a row, which resulted in 1 hate count gain, and im sure i havent crossed her in any way otherwise. Not sure why the devs havent adjusted this mechanic, so that you would get dragged to one of the less controversial private spots, but it is what it is.
-taking a peek at a girls panties earns you two like count, though im not sure if this shifts based on her current LLDH, as the chick in question had 6 love count and 10 like count prior to the event, and ended up with 6 love count and 12 like count after. I think getting slapped is better than bumming the girl out with saying you didnt see anything... getting slapped happens when the chick in question hasnt formulated a status towards you yet, or had shit LLDH with you in the first place.
-highest virtue is really strange, since while, yes, getting into a relationship with one is as easy as reaching 21 love count, if the card has more love count with someone else - she will refuse. Ive seen it a number of times with one (highest virtue) chick, with whom ive had 30 love count, but did nothing about it (had someone else - playing mono), while another guy, with over 21 love count both ways ("No doubt its love!") attempted to get into a relationship with her and she turned him down. Not sure if his chance was 0% or 5% or what, but he failed a number of times, until the chick finally lost her LLDH, putting the guy out of reach (i havent checked the exact LLDH, but her status shifted to "I think i like them...").
-based on my testing with my flytraps, i can confidently say that high virtue isnt all that great - these, given enough time, can rack up to 3, or even 4 partners simultaneously. Obviously the chances of that are slim with a regular high virtue card, given how much stuff would have to happen (or not happen) in a very precise and organized manner (given the flytraps traits and modules, that make up for a lot of this "stuff"), but its a healthy eye opener to some thinking high virtue is "the second best". All things considered, i have changed my "grading" of virtues, and claim that there are not 5, but 6 - the regular ones (lowest to highest) being 5, and singleminded trait being 6th.
-if youve made sex friends of a high virtue card, she will not put out of her own will unless coaxed into it with the "lets have sex!" call out. Thats the "base" rule... however, if she has a partner, theres a chance she will cheat on him and ask you to follow her to have sex in one of the private rooms, or even in the open, based on how horny she is. Even more of a reason to keep your girls LLDH with other guys low at all times. Dont get cucked.
EDIT:
-not a mechanic, but an interesting tidbit:
"Graceful" is the ONLY personality in the game that has separate lines for "come with me" and "come with me to fuck", allowing you to clearly tell what the chicks intentions are. In order to hear them, though, you will probably have to hunt for one with either high or highest virtue, since virtues lower than these will just ask to fuck on the spot.