His parents marriage was over; his Dad had left for a younger woman, and he was conflicted. He knew about his father's infidelity but didn't know about his Mom and wanted to find out. He followed his instincts and the results were epic.
In an instant, the mother's eyes widened, her mind went blank, and her face was ashen. When the boy's face came into her eyes, and when she realized that the man having sex with her was her son, the mother felt as if the sky had fallen. The bottom line of society, the bottom line of ethics, and the bottom line of being a mother were trampled on at this moment.
Eddie and his mother enjoy their special relationship, though she allows his other trysts without jealousy. Approached by one of Eddie's teachers, who revealed she, too, has been in a relationship with a now absent son, Eddie's mother agrees to share.