Hahaha here we go again with Cait. Here's the easy solution, just skip her content and leave her at frosthound. As most have pointed out, best boy is Brint and best girl is Brienne.It's an rpg and since it's up to you, you should be the one decides that whetever MC gonna fuck everything that walks, or gonna stick to his morals, or will companions' relationships with MC gonna be open or not, I don't recall getting asked about that (getting asked about do i prefer an open or a close relationship, cait's request you to become a cuck do not counts). This is a porn game so MC should be a cuck is not a good arguement, really.
And even if though you go with some kind of harem route, it does not vindicate that dev's shoving ntr content down your throat too.
Btw any sexual intercourse your partner had without your approval/consent is NTR.
I just felt like putting this here. If you want something more fun, I recommend you to make a new female character and name it Cait and use tf to make her similar to cait and run around the world. Imagine what two dumpster fires would cause.
Also for the sake of it, I need to remind you that the dev never planned on making this game as a power fantasy like CoC did before. Hence why most choices presented to you have little to no impact to the storyline. It flows how their writers wants it to be.