There are plenty of couples where both spouses want not sex, and they're happy.
Really? Where are these happy sexless couples?
I talk to a lot of women about relationships and sex and I've yet to come across one who admits to a happily sexless marriage .....
I've seen this briefly mentioned in several of the many books on sex and relationships I've read. The thing is, many of these couples will never go to therapy, as they don't see it as a problem. They tend to be older couples.
I've also heard that a small percentage of people are truly asexual. Their common experience seems to be that they never understood what all the excitement and giggling about the opposite sex was about in their early teens. It's relatively rare, but some of these people find each other and get married for companionship and sometimes even kids. But again, you don't find many of these people going to therapy for low sex drive, unless dragged their after marrying a partner who likes sex.
Not sure if such couples will easily admit to being "happily sexless", just like people don't generally like to admit to being happy about something that you're not supposed to be happy about.