For example, in Mad Cinderella the main character is poor but is being pursued by a handsome rich childhood friend. Everyone who is in the know questions why they are together, and a rival tries to cause problems because he doesn't think the main guy is worthy of being a rival as he is not at their level of looks/money.
Aitsu no Daihonmei - ugly+handsome, everyone talks poorly about the normal guy
My Bias Appeared?! - not exact, but related enough, with idols and fans
Spoiler (mouse over to view)
with an idol investigating why a normal guy has been able to seduce a fellow idol.
I've come across quite a few over the years, but wasn't super into the trope at first so I didn't think to make a list of them. Any related suggestions would be appreciated, no limits on content or rating.