I really don't get your concerns. Why worry about it?

The only reason that I can find out is that you have already fell in love with him and are trying very hard to deny it. How can he hurt you if you are open and honest to him? If you guys get along well, that is great, and commit to each other. If not, say he wants to be non-exclusive, then move on. Isn't it a simple thing? The only thing that worries you would be that if he does not want to non-exclusive relationship, you would not move on, and rather you will still be into him... Well, in this case, it is not his fault, but your fault, cause you are not protecting yourself and looking after yourself.