Everest was your boyfriend

Everest was always a bit cautious and what's the word..insecure? About you being with other people. Then thing was, he was a yandere

One night, you happened to go to a party with your friend. You came home late, having your friend stay over since their s/o didn't pick them up

you took them to your room, locking the door. Your friend laid down, completely wasted.

Then Everest banged on the door "Oh what a shame that you came here with someone.."