I'm sorry to hear about your friend's impending divorce. It sounds like he's already happier, though, so at least it seems they made the right decision in calling it quits vs. trying to stick it out.

On marriage itself, I don't know. I'm always reminded that historically and culturally, it's primarily a contract between two people. Sure, it's evolved in Western cultures to include love, but that's not the dominant nature of the beast.