If during the whole period dating you behaved with a man openly and honestly, and fostering their sense of hope for a serious relationship, then such a question may arise because you just do not understand your loved one.
Try to communicate more with your partner on the themes that reveal its relation to different things: the society and the people and history books, cars and music etc. Be attentive listener. He estimated the events you are sure to realize how serious and sustained his world as he is honest in expressing their point of view. Try to understand that it is referring to your partner, even if he is not particularly eloquent. It is important that the person was able to sincerely express their thoughts.
For some time, avoid discussing situations where it is necessary to discuss the manifestation or proof of your mutual feelings. In the process of communication you will see on what matters to your favorites "closed" on what your testimony, he prefers to remain silent or the conversation to other topics.
Keep in mind that thinking men different from women's. Once you "talk" your partner and realize the reason for your disbelief, everything "will fall into place." You will be a lot easier to talk to him about feelings with full and mutual trust, or you make the existence of major differences and contradictions in your outlook on life.
To understand your loved one, it is important to be very frank and open. If you love each other and your relationship you value, sincerity will resonate in your heart of man.
But we should not forget that people - being developing, so it is important to be able to find in communion "guiding" thread of understanding, trust, and, of course, sincerity.