Help.

My bf smokes a lot (weed) and i dont like it, but i force my self to let it be well because he should be able to do what he wants. im no one to get in between him and his business.. he knows that i dont like him smoking but he still does it. Some times i even force my self to smoke weed or pretend i like it just to makw him happy :( what do i do? i dont want to be selfish and tell him to stop smoking just bc i dont like it... help please