I was actually quite impressed, how well the book did with the subject matter. It manages to sound rather realistic and believable throughout the whole book. The buildup is slow and steady, starting from Jack's friends with benefits arrangement with Colin, Peter's accidental friendship with Colin, his breakup with his long-time girlfriend etc.
There is a lot of conflict in the book, because something like that cannot actually work without it. It would sound entirely disingenuous if everything just worked out. But it always feels like necessary, plot-relevant conflict.
There's also a lot of sex. All of the characters prefer fucking over talking, so actually a lot of intimacy is tangled up in sexual acts. Especially in the beginning it could get a bit... boring. But the whole beginning drags a bit as it's just setting up situations that are necessary, but only get more meaningful later an. But as the story progresses, not only the sex scenes get more interesting, all the relationships get more tangled up.
All in all, I really enjoyed the book. It's unusual, I can't really thing about any V-shaped threesomes I have read about in MM fiction, but it works, at least for me.