Can a SO/lover/fwb be like an addiction?

So I've been off and on with this guy for 2 years and he's like a good bad habit I can not for the life of me seem to quit. Everything and everyone is always in comparison to him, and being with him is like being on a glowing high. We always end up coming back to each other, but we burn out so quickly. I don't think we could truly invest much in each other, but my outlook on romance for myself is very dark. Maybe I'm just crazy. I very much don't want to be this way, but at the same time I can't seem to let go of something that genuinely makes me happy, even if I think/know it's probably bad for me. Help?
-lost and confused