I'm quite content being single. I'm 37, never married, no kids. Luckily, my parents weren't always asking me when I was getting married, having kids, etc. And, since my brother has made them grandparents, I'm pretty much off the hook!
It does get lonely at times, but I'm also very independent. I don't have to ask anyone's permission if I want to go somewhere, don't have to rush home to fix someone's dinner, etc. Honestly, I couldn't imagine having someone around 24/7. I think either he or I would have to be gone from the house for a couple of days a week. I really like my space. I am the master of my remote control.
I've gotten used to doing things alone, if no one wants to join me or being a "3rd wheel" with my married couple friends.
If someone comes along that I want to spend the rest of my life with, great; but if not, I will continue to be content.