He hasn't been getting any for like over three years? Wow, the guy is patient - just give him some already!
Seriously though, I can understand that you feel uncomfortable and maybe rather slutty but this really isn't the case - you are in a secure and stable relationship. You need to be emotionally and physically satisfied in a relationship, it is important to have your needs met and what not, what I find worrying is that you don't actually feel the need to please him, you have been trying to get away with it for as long as you can - your mentality is a little wrong, you should never do anything you don't want to, never be forced or coerced into doing something you don't fancy doing, thing is you should actually want to satisfy him, like willingly, it should make you happy that he is content.
[SIGPIC][/SIGPIC]
Love is like a merry-go-round: you get all dizzy, and then you feel sick!