So you're saying people who have been in fewer relationships are less happy in their relationships. Most of the evidence points to the contrary.
If I had a mediocre partner but I thought that was just how relationships were, I'd probably report being "satisfied" with them, even as I wished relationships weren't such frustrating things. If I thought marriage was an unbreakable bond I'd probably also avoid admitting I was dissatisfied with my partner to anyone (even myself!) as a coping mechanism as well.