An asshole, who regularly cheats on their spouse. Sometimes a practicing bigamist. Also a habitual liar who often times believes their own bullshit. A S.P.B.F. will often times regard themselves as a noble person, believing that their inability to choose a singular mate is the result of "not wanting to hurt anyone". This is however an unrealistic view, as the rest of the world views them as a bunch of narcissistic assholes.
A guy who cannot stay faithful to their partner in a previously agreed upon monogamousrelationship. Also used for assholes in a poly relationship where they are not truthful and lie about seeing others.