Bird Burglar
UK: He who covets or steals another man's spouse (or 'bird' in the argot of UK working/underclass males).
Cuckold: My wife's gone off with my best mate, the bitch.
Cohort: Don't blame her, blame your mate! He's a right bird burglar that one.
Cohort: Don't blame her, blame your mate! He's a right bird burglar that one.