I have come to realize that I need time away from other people and a marriage or even just cohabiting doesn't leave much of that kind of space. So at the very least, a relationship where we do things together, travel together, and, yes, have sex but don't necessarily live together full-time and deliberately build in some space. Is that a friend with benefits or something more? Hard to say. I suppose you could structure even a marriage that way but not sure.