Looking for a romance novel — MMC lets FMC have a lover on his terms, "dead" lover returns in a sequel

Looking for a romance novel — MMC lets FMC have a lover on his terms, "dead" friend returns in a sequel

I read this maybe 4–5 years ago and can't find it again.

The FMC has a desire/fantasy involving being with more than one man — I think voyeurism was part of it.

The MMC finds out about this. Instead of shutting it down, he says something like he'll allow it, but only on his terms, and he'll choose the man.

The man he picks becomes a real, trusted friend to both of them — not just a physical thing. The three of them build a genuine emotional bond and have a good dynamic together.

Toward the end of the book, there's a plot to kill either the MMC or the friend. The friend ends up sacrificing himself and appears to die saving them.

There's a time skip of a few years after that — I believe the MMC and FMC have kids by this point.

Twist: the friend didn't actually die. He comes back.

I know there's a sequel to this book that follows that reveal, but it hadn't been released yet when I read the first book.