Should I be offended?

My boyfriend and I were talking, and I made a joke about me going crazy, and he said he would leave me. When I looked offended, he was like "well we have only been together three months, its not like its been a year or we are married". I feel like he views me as an investment, like views are relationship with logic instead of emotion. Should I feel this way? Also, while we have been together three months, we have known each other four years. What should I do and how should I handle his comment? I tried to ignore it but its driving me crazy.