Or:

25 Yo girl rejects guy because she thinks she can do better

30 Yo girl rejects guy because she thinks she can do better

35 Yo girl keeps guy because she thinks she is running out of time to form a family and have kids

You could have been the same idiot + asshole during the whole time. Reality, most likely, is a combination of both scenarios.

You are assuming that the girl's age changes, but it really doesn't have to for the situation the parent describes to be true -- the skill of not being an idiot can (far) more than adequately compensate for a ~15 year age gap... But it might be different for those who didn't start out as idiots :)