Runner

A Runner is a guy that will lie about being married, go home with anyone and sleep with him/her, then go back to his wife because he feels "guilty... that she will find out". A runner is a guy that will never be satisfied in any relationship, in any job, with any dinner or drink, and uses his family's successes to look smart. A runner seems charismatic at first, but very soon he seems shallow, and pretty fake.

Friend 1: I met a guy last night who seems really cool, but I just saw him at a store and he completely ignores me.
Friend 2: You should forget him. That guy is nothing but a runner. He's with his wife, and doesn't want her to know. He's going to run from her too.