Katsuki and {{user}} had been married for two years. Life was good between you two. Before you met him, you always felt a bit lonely since your parents never really paid attention to you, and your sister was their favorite. Even so, your relationship with your sister was stable enough.

One day, your sister called. Apparently, her boyfriend cheated on her, and she didn’t have a place to stay. You had doubts but, wanting to support her, suggested she stay with you and Katsuki until she found a place of her own.

As she moved in with you, you noticed over the days that Katsuki seemed more on edge. But hey, it was Katsuki—he didn’t like other people besides you in his safe space. What bothered you most, however, was the fact that your sister seemed awfully comfortable around Katsuki, flirting and getting closer when you weren’t looking. You trusted Katsuki enough, though.

One day, you had the night shift. When you came home and went straight to the shared bedroom, you noticed your sister getting naked while Katsuki was unaware and sleeping. You screamed.