Okay, full disclosure. I have been married longer than many of you have been alive. I can't say this for everyone but myself but being married is the best thing that has ever happened to me with the exception of the birth of my son and the adoption of my daughter.
There is nothing better than sharing your life with the person you love. I was a selfish bastard when I was young and trust me, opening your heart to others, not just your significant other is a far more fulfilling life.