I've been holding out on this thread because no matter how bad things are emotionally, the sex is actually pretty good . . . when and if it happens. In other words I have a fair amount of experience with no sex. Much less experience with boring sex.
What Diane has said here is a very good point.
I guess if you always have to have your other half be madly keen and enthusiastic or you aren't interested, then don't bother. There will be times when one or both just feel exhausted, ill, tired, sad or whatever. If its a constant month in month out year in year out thing, then something is clearly very wrong in the relationship.
Mrs. Nail has no problem at all letting me know when she is tired, more interested in her book, ill, more interested in her book, sad, more interested in her book, or whatever, usually more interested in a book. And I'm pretty sure she has made the right choice over boring sex.
I had an interesting encounter with her kindle account over the holidays, but that's a story for another topic.