Hmmm. that's a really good question. Hobbies are supposed to make us calmer and happier. so, it would stand to reason that quilters would be more happy in a relationship, especially if that relationship supported the having a hobby.
I would hazzard a guess that the even more stable ones are ones that both spouses have a hobby supported by the other spouse. my DH does woodworking. So he has times he is not under foot and enjoying himself in the shop. I have times I am not under foot and enjoy myself in the sewing room.
the problem for us is when we are both not under foot and nothing gets done but our hobbies!! life tends to still move forward. :)