The way I see this concept is that perhaps the wife had a number of traumatic, or somewhat traumatic but cumulative, experiences with men in her life and he might be the nicest guy she's met, which is why she chose him regardless of looks or experience. Thus, if he protects her back in time she may end up wanting a better looking decent guy later in life, which I think may be the tragic beauty in the ending. He saves her from the trauma that ended up im her "marrying down" but she ends up with someone else who's a good man and better looking. I'd just a theory.
For this to work and not just be like "LOL VIRGIN SIMP1!1!" we have to believe this guy is a romantic and wishes for a love that has few partners or just one at all. Perhaps if the male MC had a few partners as well but still had the same dream, it would reduce the "simp" insults. Or perhaps if he was good looking it'd help. I think neither the idea of a one-partner lifelong love nor the idea of being open to multiple partners before choosing are wrong, neither should be shamed. But it's clear what the comment section wants to witch hunt about.
I also wonder how this story would play out if it was the reverse genders. An ugly girl who a great looking guy marries, who has the same ideas about love and wants to be her man's only love.