I've been out since I was 21 so that would be about 17 years now. I've had two 5-year relationships, one 1-year, and 8 months. So at least for me, the majority of my life has been coupled.
Having said that, and being single now, when it seems so difficult to find a guy who is right for me, being single feels like an eternity. At this point I'm pretty content being single and being able to do whatever I want. I want a realtionship again, but I'm not going to torture myself over it. My Golden Retriever is about to have puppies (which is a HUGE deal for me), I've got new responsibilities in my career, and I've learned to be comfortable and happy with myself.
I think gay men shouldlearn to be single, not for promiscuity and amassing as many sexual experiences as one car, but to be comfortable with just themselves. When a right man comes into your life, you'll have a better appreciation for couplehood and for being single.
That being said, my dating experiences have shown me, more often than not, guys who say they want a relationship really don't, and get terrified when faced someone who does want one. And mostly, I've found, this fear comes from some insecurity. It may be financial, it may be social. but its that insecurity that keeps many gay men single, IMHO.