Give him your trust. Believe that even if you do get hurt you will be ok and your life will go on. You are only half in the relationship feeling like this. Unfortunately loving someone is about losing control which is very scary but the way I see you are either in a relationship and not completely happy due to fear, insecurity, doubt etc or alone and not completely happy either (if you want to have a partner). So either way you won't be happy. May as well give this relationship all you have and experience it truly and wholly or break it off and stay single. Tell him your fears, not out of wanting reassurance but just so you are communicating and opening up. How can somone fall in love with the real you if you are barricaded? There are no guarantees in life, nothing is permanent so just enjoy the moment. The relationship won't fail because you have opened up. It will fail coz you haven't and then you start the heart-break cycle all over again.
Some people are drains and some are radiators... Keep clear of the drains and hug the radiators!