You haven't had sex with the right person yet. I'm 29 and my last relationship started about 4/5 years ago and it was the best I've ever been treated. Genuine care, love, and selflessness. I've never had such good sex before. It took time to figure out how to be sexually comfortable and trust that person.
You need to keep meeting people until you meet a really awesome person that you find yourself attracted to. Hopefully getting to know that person will reveal how awesome they are.
I'm basically looking for a best friend I can have sex with. I think that would be the most fun person to spend my life with. Though everyone is different and others may have new perspectives.