I was in the same boat. When I was in my early 20's, I decided that I wanted to grow up and start on my career. Most of my friends had different priorities like drinking and partying. While I liked to go out on occaision, every night and even every weekend was too much. My husband had been my best friend from the day I met him. I found it was easier to find a boyfriend than a really good girlfriend...
I still have the same group of friends and we are all at the same stage in life, but we have grown apart and see each other at our kids' birthdays. I have one friend from that group that is my closest and our priorities are similar. She was really my only friend for a few years because I had different priorities (like working) than most. Then I hit 30, had kids and realized that I needed more for myself. I made friends at work, and joined a playgroup with people that have the kids the same age and same ideas as me.
I realize you don't have any kids, but I am going to echo what everyone else says, join a club, group or anything that interests you. Make sure you make it a habit and you will find someone that has the same interests as you.