When to move out?

I think that your 22 year old friend is a very responsible person. I'm sure his girlfriend appreciates it very much that he's willing to provide her a stable environment where they can foster and grow their relationship even more instead of moving out at the first chance he gets just for the sake of moving out. I think many young people (myself included) move out at the wrong time and for the wrong reasons. It sounds like this family is very well grounded and are good at communication because that's really the key to relational happiness. This is most evident in the fact that the 36 year old brother still happily lives at home. I think in older times it was seen as honorable to live on in your father's house, but somewhere along the line that changed, but with the economy how it is today, I think that society will move back to that kind of living arrangement, and I think society will benefit greatly :) So to answer your question, I don't think there should be a minimum age, and it's definitely all about happiness.

I think that it shouldn't matter what age you are, if you want to move out and have the means to do so you should. But if you want to stay with your parents and they want you to be there then by all means stay.