The values that lead people to say it's OK to shack up--and to "move on" when the shacking gets tough--don't just disappear when marriage vows are uttered. In my own 25 years of college teaching, I noticed that most of my own students chose cohabitation over marriage, and few of the marriages they eventually did enter have endured. The victims tend to be small and helpless. The trend is getting worse; look how many people here defend it.
Absolutely. I've always been amazed at the number of people, here on a conservative forum, that are shacked-up.