I don't think I really love my boyfriend
Oh is that so? Why do you not love your boyfriend?
Not really, I'm just confused. I don't think I've ever known if I really love him.
That's understandable and truely admitting you're in love with someone can be a scary thing. Being uncertain is totally normal and until you find that answer you're under no obligation to say for sure that you love him. Whichever answer you come to, it'll be the right answer for you and I support it.
I just want to break up without hurting him.
That may not be possible, but I still think it's important that you break up with him if you don't have any feelings for him anymore.