You hate women who flirt with you, glow in the flattery you shower them, only to end up telling you that they are in a relationship. You hate it, because nothing drives you mad than the discovery that a woman has ‘friendzoned’ you and she is using it to build her self-esteem.
As the joke goes, there are men who feed the cow, and there are those who milk it. Friendzoned guys are the classic feeders of cows but never taste the milk in the long run.