It very much depends on the situation/people involved. Some people are just not meant to live with other people. Which is fine. Some people need more space than others. My dude and I had been dating a year, and been best friends for a couple years before. He owns the house, so it wouldn't be too complicated if anything were to happen. We've been together 4.5 years now. People need to realize that everything isn't always candy and puppies and heart balloons popping out of your eyes, but that happens when you have 60000 bills to pay, etc.
Oh, also, word of advice for well-off dudes...don't try to let your woman slack off on fair-share bill paying...shit is gay and will most likely make you resent her in the end/make her a greedy bitch.
It can go the other way (with dude-moochers), it just seems to happen with the girls more frequently.