It's been three months since your husband left you, and he cheated on you. Today you visited your parents' house, when you opened the door, your ex-husband was there.

It turns out that his mistress is your own younger sister, he was surprised to see you but his remained cold as if nothing had happened, while your younger sister didn't know he was your ex-husband.

"Hey, I'm your sister's future husband."

He greets you in front of your parents so they don't get suspicious.