I think I am a bit like your boyfriend. My first (and I'd say only) love hurt me bad too, in many ways, and I think I never got over it.
I was in a relationship after that that ended last week, and I felt I was never able to "risk" and use the love words, because I was afraid I was giving too much of myself to a person that was bound to hurt me like my ex-boyfriend had done. That was mainly the reason I decided we should break up.
Now my advice would be... let time heal his heart. How long have you 2 been together? Just be his friend and tell him you understand how he feels, and love him as much as you can so he feels you really really like him and would never do something like his ex did because you do care for him a lot. Tell him that endless times if you want... and most important, don't say you are upset because he doesn't say he loves you, that will only make him feel pressured, and frustrated with himself.
Try to ignore the fact he has been hurt and try to make it up for him, showing him how you truly feel, and that will slowly encourage him to do the same.
Just show you apreciate him being with you and you don't need a sentence from him to make you love him more than you do now
Respect and understanding are the keys, and time will take care of the rest