One of my friends who is also anti-marriage - although for different reasons than mine - sent me his explanation for avoiding a second marriage. This is an excerpt:
We think a relationship will help us be who we are, and yet to preserve the relationship we end up lying about who we are. You long for some adventure, some passion, something that you can't fabricate; yet we feel it must be kept secret because it threatens what you have.
When I was composing my answer, I considered his last observation - "it threatens what you have". What do you have as a married person that you don't have as a single person?
I've made several comparative lists today. While nothing's been compelling enough to change my mind about the institution of marriage, I'm beginning to understand why so many people prefer it. It reminded me of after I broke up with my first husband. Afterwards, I joked that he got custody of all the friends, and I got custody of the cat. I never understood why he felt he had to vilify me. But he hated to drink alone.