Well, what gets me isn't so much the usage of marijuana as much as the lying. I'm in the same boat as you, in that many of my friends smoke marijuana yet I refuse (I would say it's a moral basis, but that's not quite right...more of a "my mother would kill me" sort of morality, I suppose?). At any rate, if he's not willing to compromise and work with you about it, and if he's going to lie to you about it, I'd split. I am sorry to have to advise that.