Your monogamous wife has a slutty BFF who got her drunk and gave her drugs. Now a random guy from the bar is about to ejaculate inside the mother of your children.
Is it really cheating if Mother Nature is telling your body to do it? No. Give in to your urges. Give in to nature. Enjoy the power your pussy gives you.
He has bigger muscles, bigger balls, and a bigger cock than your boyfriend. The tingles you feel right now are Mother Nature instructing your body what it needs.