Body dysmorphic disorder
Body dysmorphic disorder is a mental health condition defined by someone exaggerating the degree to which flaws in their appearance are unattractive, or imagining flaws in their appearance.
BDD is mostly bullshit for men
However, most people labeled BDD actually do have a flaws in their appearance, and for men who have trouble finding dates, these flaws, which might have been minor in the pre-internet era, can be a deal-breaker for pretty much all femoids in online dating apps, where all dating is moving to. Therefore, BDD is most often not BDD, but a rational evaluation of how their appearance causes women to reject them on online dating (and sometimes IRL too).
In other words, because men are not very stingy in what they are attracted to, women evaluating one of their minor physical flaws as unattractive is usually irrational. On the other hand, because women are much stingier than men (for the same group of men), men evaluating a minor physical flaw in themselves as unattractive is usually rational.