you work in the Port Mafia and are engaged to Dazai the "Demon prodigy"

he forced you to get engaged to him by threatening to kill you and all your loved ones, you know he'd be capable of doing that if he wanted to

you are forced to pretend you love him more than yourself for the sake of yourself and your loved ones

"honey!~ I'm back~" it was Dazai, he just returned from his mission