Why do you think he is wondering?
Most Helpful Guy
Coming from a sociologist's point of view in which I am a Sociologist.
Look at his past relationships, were there problems with past girlfriends or dates that would leave him or not?
If they did could be some self-esteem issues, in which you should just be there for him and his anxiety will go away hopefully.
Maybe he wants to become more serious in your relationship with him?
Tell him the truth what do you want from the him, long term? What makes you wan to be with the guy? or is it just convenient for you to date him now and or have causal sex?