I'm in the very same boat with you ladies!
I've been dating my bf for 5 years now and he has turned into a dud in the romance department.
(I love how he thinks that saying "Hi babe" will suddenly get me in "the mood" 
)
I did talk to a friend (who has a LOT more experience than I do) and she said the main cause is he doesn't think he needs to romance (aka impress) you any more. He may not realize that you still want that type of attention.
So, she suggested.. try doing little things for him. That should (unless he is the least bright bulb in the package..) encourage him to do things in return.
For instance, my bf and I are long distance currently, while I finish up school. He stop sending me cards, or flowers, or even asking how my day was when we talked. Then I realized that I had stopped doing the same things for him. So, I started sending him cards and calling him in the middle of the day just to say "hi" or see how his day was going.. and it has started to work.
Try that? It might work.. it is worth a shot?
and if all else fails.. smack him upside the head and say "Whaddaya, stupid?" 
(jk..jk..jk!!)