Boy: "Did you hear Ellie is going to start working here?"
Girl: "Oh shit! She's a homewrecker tell all the girls in the club to put their husbands on lockdown!"
Girl 1: "Did you hear Taylor is fucking the DJ?"
Girl 2: "Isn't he married with 3 kids?"
Girl 1: "Yes he is but she's a dirty homewrecker that can't find a man of her own with that dumpy ass of hers so she's gotta steal somebody else's husband!"
Once one's life is ruined in such a way, their 'home' is considered 'wrecked', hence 'Homewrecker'.
Bob: Fuck me, I'm doing a u-turn just to see her again!
Bob's life is eventually ruined.
Country singer Gretchen Wilson has had a lot of experiences in high school with losing her dates to homewreckers, so she included the subject in a song on her album "Here For The Party" and called it "Homewrecker."