I don't like my girlfriend smoking weed, and I told her it's either the smoking, or me. Does this make me a bad person?

I don't care if my friends or if other people that I don't know well do it, it's their lives. But when it comes to a significant other, my "other half" that I will want to spend the rest of my life with; that's when it becomes an issue for me, and I don't know if I'm doing the right thing.
I don't like my girlfriend smoking weed, and I told her it's either the smoking, or me. Does this make me a bad person?
Post Opinion