[Campus+male stand-in+chasing wife+fighting and grabbing]
He missed her because of a joke he made when he was little.
In the days of separation, only he suffered the pain of missing her. She had long forgotten the time they played together, or maybe she was unwilling to admit the childhood joke.
She didn't realize that she accepted the other person's confession because of their similar appearance.
It's not that she doesn't understand love, it's just that her emotional sustenance is not here.
When they meet again, she is still heartbroken, but she has to pretend not to know each other and hurt the other person.
Intention: stand-in