How do I break up with my boyfriend?

I’m 17 and have been dating my boyfriend, also 17, for about 7 months.

I feel like it makes me a bad person for saying this, but I’ve lost feelings. He genuinely is a great guy and treats me really well. It’s nothing on his part that’s making me feel this way. I just feel trapped I guess? I don’t feel like it’s right for my mental health that I’m in a relationship right now.

But if I leave I know it will absolutely crush him. I’ve known him for like 9 years, and we were good friends for all that time before getting together. So I know that he had one girlfriend before me and she broke his heart bad. I’ll ruin him again by doing this. I do feel bad but I know it would be worse to stay in a relationship I’m not actually invested in right?

Is there any way to be tactful about this? I really don’t know what to do here. Any help would really mean a lot to me

EDIT: I didn’t expect this post to get so many responses! I appreciate most of them. I’ve taken into account many of the things people said and as much as it’ll suck, I will be having “the talk” with him tomorrow. Thanks again everyone :)