I expect there's greater correlation than you're suggestion implies. I've never run across a guy that hasn't been intrigued by twins at the same time (which would include girl-on-girl action); I've never known anyone into pee/scat (nor have any of the women I've been with). It would be exceedingly rare to find a guy that doesn't like girl/girl, while it is also fairly rare to find someone that likes the more demeaning kinks (or at least to find someone that admits to it). When you do find the latter, they tend towards sadism and misogyny - probably because they fear women in reality.
(a) Kink shaming is not really liked on these forums,
(b) I believe you that you've never come across something like that, however it is dangerous to extrapolate from such a small sample size, especially since people hanging out both tend to have similar preferences from the beginning (not necessarily sexual/kink/fetish prefs, but in general) as well as only admit to those common in their peers.
Of course we also have to differentiate between "real life" kinks and "story" kinks. E. g. I wouldn't really be into multiplayer action (threesomes, orgies) in real life, while it can be nice in a game (or a porn vid or what have you).
You're right, but the problem is the level of games that are 1 guy to 1 girl are basically nil. Even the ones which don't allow multiple partners like Sunshine Love or Melody still allow the MC to fool about until a crunch point. So if you selected that tag even those games wouldn't be included.
I gave up on Sunshine Love when the dialogues became too tedious and long winded but in Melody you can even have two multi girl endings (Melody and Sophia with or without Xianne). Hoever, IIRC it does allow for "one true LI, no fooling around" if you so prefer, so I would count it as a game suitable for 1 to 1 stories. Admittedly, not all girls can have an ending like this (Sophia and Xianne again).
But yeah, if you prefer "Young man comes home after years of absence to his landlady and roommates and discovers his sexuality, mostly vanilla but a bit of spanking lite" you have a larger choice than with other preferences, that's for sure.