Awesome post, agree with most of it. I do think though that even if marriage wasn't a legally binding contract you'd still get idiots that are obsessed with this tabloid gossip. Sadly, there's a very genuine public appetite for this information. See the success of Celebrity Big Brother and Heat magazine. If somebody is a successful director or actor then they apparently owe it to the public to give up all their privacy and be judged.
All these people obsessing over celebrity break-ups would react very differently if one of their friends in real life cheated on their spouse.