I'm in this exact situation.
Except I'm 27. And I don't have people inviting me out to go drinking all the time.

I don't have any social life. When I was in college and right after I graduated I tried a few times joining clubs or going to club gatherings, but they were never worth the effort. They weren't all that enjoyable, and none of the people there ever felt worth my time.

I don't have any particular need or desire for a social life, but I do desire companionship. I feel like a girlfriend is all I really need.
Of course I'm not trying to say that I need a girlfriend to be happy. I'm satisfied with many aspects of my life. But in terms of friendship, I feel like just having one person, a romantic partner, is all I need to satisfy me.

Of course meeting people is next to impossible. I've been on probably 3 or 4 dates in the past 6 years.