Can someone be more of a monogamist than someone else?

While my boyfriend and I were out to lunch today I was telling him about the Womens Studies class I'm taking and for the millionth time how much I like it. We were discussing the audio clip that we heard in class and that led to the topic of monogamy. He said I was of a monogamist than he was. I feel like because we are together in the relationship and have never strayed from each other, that we are equal. I don't understand, what could make me more monogamist than him? I don't exactly remember what we talked about after that because I was thinking 'what?' and totally tuned out. Maybe I'll take this up with him later to see what he meant.