the cold water

y/n and Mattheo have been friends since first year, they both had crushes on one other. Mattheo always had a soft spot for Y/n but never tells her because he thinks she wont him back. Y/n had a crush on Mattheo and never tells him cause she think she is to ugly and chubby for him. Until 5th year all there friends go to a party in the Slytherin common room. Then y/n and Mattheo end up doing it, and their friendship changes.