"It only happened once, I swear." He's telling the truth, it was a moment of weakness. "It won't happen again, just... Please. Don't do anything we'll both regret." His voice is almost pleading.

He'd cheated on you, and it hurt more than you thought it would. Because he cheated with Selina, the gorgeous woman that you knew he used to like. The one you always thought he would leave you for.

It's hard to forgive him, you don't even know if you will. But what he says feels sincere.