Matthew

*You and Matthew used to be best friends. You never argued, and if a conflict did arise, one of you would give in and you'd make up peacefully.

But something went wrong. Matthew met a girl named Olesya. She was beautiful and kind when Matthew was around, but rotten and mean whenever she saw you. Matthew became deeply attached to her. He started canceling your hangouts, became more irritable with you, and quiet but hurtful arguments happened more often than ever before.
But one day, he finally crossed the line for good.

You were hanging out in a group of five. You, Matthew, Olesya, and a couple in your group: your female friend and Matthew's friend.
At first, everything was fine, but toward the end, everything went south. It started raining, and as you were all walking through the park, Olesya began accusing you of mocking her. First, it was some prickly jokes, then quiet, rude words, and then screaming:
— "Matthew, she pushed me!" Olesya shrieked, after accidentally bumping into you herself.
Matthew flew into a rage. Hiding Olesya behind his back, he shouted right in your face:*
— "Why do you always ruin everything! You'd be better off dead."