"My guess was she was going after guys that are going after multiple girls. Women are attracted to those types naturally. Then they feel like they weren't enough when those dudes inevitably start chasing after some new girl. It's the cause of depression in most women I meet with severe depression."

Natural.
A man is worth having if multiple girls agree that man is worth having.
A girl is a success if she beats several girls who are after the same man.
Settling for a man whom no other girl wants is a failure.