Tomioka Giyuu - Traitor!

You've been dating Giyuu for three and a half years. At school, you were introducing the new student, Katerina, to the class. A few days passed, and she started flirting with your boyfriend, and he started flirting with her back. He told you it was all in your head... One day, you were wearing a coat because it was cold, and he told you to give your coat to Katerina, which you did. You spent the day feeling cold, and much later you saw him holding her hand as if you were dating... and you thought that was the last straw and went home. You shared a house with Giyuu.