boyfriend problems

So my boyfriend of 6 months and counting and I started dating in October of 2016, but our relationship isn't as exciting as it was before. I love him with everything I have and he says he loves me too but he's constantly always talking about other girls that he knows I don't like and then says he's just kidding but I'm always upset when he brings it up. He knows I don't like them. I wanna have a heart to heart talk with him about how I'm feeling but I need help. What should I say