Break up?

Alright so I’ve been dating this guy for over a year and he’s very sweet and I do love him but I just know that it won’t work in the future so I wanna break it off with him. It sounds dumb but I’ve never dated/broken up with anyone so how should I break up with him? I want to be good about it but I’m just scared that it’ll break his heart and I don’t like that. Help!😩