We have been together 17 years now and have two kids together. A relationship is a whole lot more than just sex. You end up in your 40's lonely with no one to share anything with and all the good women end up being taken. I have plenty of friends just like that.
On the flip side, have friends who are 40 plus. They are happy being alone because they had the wife, kids then divorce. Some more than once. They all say "It aint worth the hassle, I'm not doing it again and I'm happier on my own"