I see you put different weights to actions, with the who being far more important than the what, if I understood it correctly.
I'm different in that I see sexual activity of any kind as something you'd only do with someone with whom you share at least some level of a deeper connection, not something to be done casually, so "sexual activity with a stranger I'll likely never see again" is completely out of the question.
So the what by itself has a lot of weight to it for me and would only be done with very specific (and limited) who's. They'd always be linked instead of being distinct and evaluated on their own.
With that said, this being a very American Pie-esque porn game makes it all whatever. Just enjoy the ride.
I'm not trying to explain my perspective on sex, but what appears to be hers. After all, it's her perspective on sex that would influence her actions, not my own.
Both the what and the who are factors for most people, as are the likely consequences. However, she's clearly comfortable with casual sex in general so the "what" is of diminished significance for her personally.
The difference in perspective seems to be that whereas you say you only would consider sex if a deeper connection exists, she's the opposite from what we've seen so far. It's easier for her to have sex without that connection because there's no lingering changes in her existing personal relationships and there's no existing connection that would amp up the emotional attachment. It's scratching an itch and moving on.
But if she has sex with MC, it'll be much more than just scratching an itch because of their existing connection and there wouldn't be any simply moving on. If she has a hesitancy to get with MC, it's likely not due to the sex act itself (the "what") but instead because of who he is in connection to her (the "who") and how it'd irreversibly alter their relationship going forward (the "consequences").
Edit: I just wanted to add that one thing that makes OS so enjoyable to me is that, much like in real life, the LIs have different perspectives and comfort levels with sex. There's people like Moonsong and Parker who are clearly sexually open and experienced that are quick to get in the sack, and there's people like Ruth (who have been with only 1 other guy and only after a lengthy and romantic courtship) and Coldsnap (who is still a virgin). And as the harem forms, there's going to be LIs that are open to the idea and ones that aren't.
To me, that makes it way more believable and interesting than if all of the LIs were either chaste or promiscuous with barely any variety.