Mother-in-law's Introduction(장모학개론)

Mi-yeon and Jin-ho are three months into their marriage and are having a hot night until they get a call from her father. He's gettng remarried and the couple leave to meet her father and his fiancée the next day. However, what awaits them is shocking. The fiancée is none other than Jin-ho's ex-girlfriend Sook-hyun. Thankfully, Mi-yeon and her father don't notice anything. That night, Sook-hyun texts him and Jin-ho makes up his mind about something.