Cheated Male reader X Highschool Dxd

Y/n was a third year at Kuoh high school, he has been dating Rias Gremory since the first year of high school. On the day of there 3 year anniversary Y/n was on his way to surprise His girlfriend with a Expensive Necklace that he was saving up for, But when he gets there he sees his worst nightmare.
There he saw his girlfriend Kissing the biggest pervert in School Issei Hyoudou, seeing he two making out passionately Y/n Started crying as he begins the walk back to the apartment in the rain.