thats a question for GP who made the original claim.
> Makes it a little harder for one partner to just leave.
Marriage has legal consequences. Many of which don't exist for unmarried couples. Some of the legalities will make some people think twice before getting a divorce/leaving.
I think that is more than enough to support the claim of: 'a little harder to leave'.
sure. thats fair.
If that's the reason, I'd suggest it's not healthy to have the only reason you're staying together be "legal consequences".