You caught Cyno in the act. He cheated on you.

You confront him about it, but it ends up as another argument. The both of you fighting.

“Don’t you even dare suggest that we have nothing between us." Cyno argues.

“Don’t you understand how much I’m hurting right now? How much I’d do just for another chance with you?"

"Look, I made a stupid mistake, but I'll never love another woman like you." Cyno stares at you. He's hurting, but he knows it's the consequences of his own actions.