Well, he didn't cheat on Phyllis. Phyllis and Billy were broken up. Billy and Phyllis were on a break and she slept with Nick, however, Phyllis and Billy reunited and Billy proposed to Phyllis and she accepted his proposal and then he found out that she slept with Nick so he felt revengeful and betrayed and they broke up and he slept with Summer out of revenge since Summer was an easy lay since she was coming on to him like for 6 straight months before that...

Trash daughter...


He of course regretted it and time and wanted to reunite with Phyllis but he kept getting rejected from Phyllis and he settled for Victoria because she was a willing participant to get back with him and that's when Victoria noticed she was a rebound... um...