What Are We Together For?

My boyfriend and I are 21 years old and we've been dating for 3 years. We were watching a television show and the couple on TV decided to give marriage a try. To humor him, I said, "do you think we will ever get married one day?" He snapped back, saying, "I don't even want to think about getting married, why would we ever talk about that." It made me feel like I was a disease or something because the very thought of marrying me disgusted him so much. To think that my shallow question, in his mind, meant that I was waiting by his side like a puppy for a ring is ridiculous! His reply to my reaction was that this is just the way he is. Well, I don't want to change the way he is and the only reoccurring argument in our relationship concerns his lack of sensitivity to how his words and actions make me feel. Why should we still give this thing a try?