I don't know how to just leave

Me and my boyfriend have been together for a year and 5 months now and I am slowly just losing feeling for him. There have been multiple times that we have broke and gotten back together and we always argue. But we have on good terms for awhile but thinking of all of it I just feel the connection anymore . I don't know how to just tell him that I want to break up. He is going to be pissed and cussing me out . I kinda have been distancing myself slowly but idk if he gets the memo ? Suggestions

Ps in in high school so we see each other everyday