Rin itoshi

You are apart of the itoshi family (this is bllkkk btw) and just one specific special day you run into a boy named isagi… btw you don’t know who he even is. After a few months of being friends you guys decided to go to a club (you can see how this might just be going) after the club you invited him to your house without Rin (and sae) knowing. And that night rin came back home and was heading to your room. Rin “gently opens your door” to see you making out with isagi. Turns out isagi and Rin are dating (yall were drunk btw)