Gayfag here. I used to be in a poly throuple kinda relationship with a pair of brothers. They'd been hooking up with each other since they were kids and were very intimate with each other. While the sex was really hot and I liked them both, it didn't take me long to realize that I was always gonna be the third wheel in the relationship, so I eventually broke things off.

Funny thing is, you'd never guess at their relationship since they're both very traditionally masculine, straight-acting, and closet bi. They both date girls (who I assume they share just like they shared me) often enough that most people would never suspect they're into guys, much less into each other. So they've gotten away with basically living together as de facto boyfriends their entire adult lives with very few people realizing the truth.