Men have different standards or values for themselves than for women, generally speaking. Some buff up in gyms, some grow goatees and dress in hip clothes, others get tattoos etc.
I may be not getting the gist of your question, but generally a man who has a woman more attractive than himself sees it as HIS accomplishment, in having been able to attract her.
Maybe he trust her, some people worry their partner might cheat because of their looks. Them not being as attractive may not have the same opportunities (that is without paying for it ). But he might trully love her and her beauty knowing she respect him and loves him as much as he does her.
This is a very weird question. I can see a guy getting jealous of another guy who is more handsome, but I think whoever wrote this has some gender confusion issues.
This is a gross generalization.