Harley is the archetype of the "interloper." The film uses him to illustrate how seduction works in the real world. It rarely starts with a physical act; it begins with emotional validation. Harley validates Judith’s ego. He offers her a business venture, creating a professional pretext for their time together.
But here is the confession I will never make to Elena: I understood why he did it. Temptation Confessions of a Marriage Counselor
The temptation confessions of a marriage counselor would fill a library. They include: Harley is the archetype of the "interloper