son-zoned

When a MILF is seemingly interested in a younger man, only to have it turn out that she views him more as a son than a probable lover.

"Dude, I thought I was on the verge of scoring with Mrs. Jenkins but now I'm starting to think I've been son-zoned the whole time.

Son-Zoned

Adj. Is when an older lady rejects the advances of a much younger gentleman.

Susan: did Aiden hit on you over the weekend?
Vicky: yes, he did. But I son-zoned him: he's just a few years older than my kids.