Do people actually care if a rich, beautiful girl dates a poor guy? Do people actually care if a 10/10 woman dates an “ugly” guy? People will see couples like that and say, “He’s out of her league.” Do people actually care about this? If Jessica Chastain, Angelina Jolie, or Alexandra Daddario dated a 25-year-old man (or woman) who works at a grocery store while attending college, would people actually care, judge, and look down on it? (Real people, not just keyboard people.)
What you’re describing sounds like a difference in mate value. It’s a combination of any desirable traits like looks, fertility, resources, or anything else. We might spot an apparent difference in two mate values, but the US doesn’t have many rules or norms around mismatched pairs. Other cultures might though, with rules around bride price and such.
Most animals are pretty good about assessing their own mate value from physical and social signaling and tend settle into matched pairs more often than not. There are some cool social experiments that repeatedly prove this out, but I don’t have any links handy.