Sexual Orientation Options Unclear

So with this new household there have been some developments that have me scratching my head.

So Shawn kept flirting with Shayne although they were in a woohoo only friendship so Shayne had to keep reminding him that he doesn't want a romance.

Well, in time Shawn started dating this other guy. He even kissed the guy in front of Shayne but there were no negative consequences. Now, Shawn just called Shayne to say that he thinks Fuifui is going to propose to him. He asked Shayne what to do.

Shayne now has the "Single and living it" lifestyle so it shouldn't affect him. But for some reason, I am affected by this!!! I'm trying to remain neutral but failing.

Anyway, my point is that if Shawn and Fuifui get married, I'm afraid Shayne will lose his woohoo partner but maybe I can get some further insight into how the mechanics work. Because I'll be able to see if Fuifui gets jealous when Shayne asks Shawn for a woohoo when Fuifui is in the room.

I wish someone could explain in more detail how exactly the settings work so I don't have to do so much experimentation. Ugh!