What rights do people have when working in a right to work state?

My boyfriends boss hates me. I've met the guy once, for around 15 seconds, and he just took an instant disliking to me. He says he knows my "type". First of all I find this upsetting that I am being shoved into a category without him even knowing me but to make it worse its beginning to effect my boyfriend at work. His boss is constantly putting me down (along with the rest of women kind) saying that all I want is to ruin his dreams and his life and make him miserable and I won't stop until I've done that. WHAT?! Who does that?! So, not only is his boss slandering my name all day long at work, but he has now made the ultimatum to my boyfriend that it's either his work or me. Why you ask? Because on the way from my house one morning he got pulled over and was late to work. So, its my fault and I have to go. My question I guess is can his bos fire him for not breaking up with me? Why should I have anything to do with his job? HELP!