It was cousin, but then the dev changed it to avoid patreon clapping his cheeks. There are a few games like that, where it started out as incest, or it was obvious incest and then the dev removed it, so not sure if those count. That game you linked in particular wouldn't qualify as romance as it's just some sexpest mc who catches dick disease and the doctor tells him he has to fuck X amount of women, or he will die. It's not a bad game, definitely better than the sequel game, for sure. His best game is
https://f95zone.to/threads/lust-life-v1-6-241029-extra-astaros3d.19939/ and that might work on this list better imo. If you haven't tried it, it's pretty solid.