It may be a shock to your wife that what you want is more than a sandwich and a blowjob, not that they aren't both great. If you look at sex from the LD side of the equation mostly you see that it's not that important to them and meanings attached to it is subtly negative.
If you are doubting her actions because there is a lack of foreplay, Flirting or other "signaling" behavior you got to know that you're both probably so out of practice at those things that is not going to be easy just to go back in time.
I'm sure that your wife would like to fix things in your relationship as well and may be just going for the first thing that she thinks you want the sex. Probably in the time that you were starving there were a million frustrations, rejection and problems that you felt from your half of the equation.
You want out and suddenly she's interested, after all the time and all the things you did to get her interested now she good to go, I can understand the frustration.
I had a longer relationship when I was younger with a woman and we had developed quite a struggle over sex. When it became clear that I was finally done with the relationship she would do anything to keep me, I think I abused that power a bit too much. I was just too young too see my part in the whole thing at the time so imagine my surprise to find myself with similar sexual problems in my next relationship.
I'm just assuming here that you're not really that intimate with each other and you have learned to not share what's going on with yourself, how your thinking and feeling. Your marriage is probably suffering from what feels like a lack of intimacy as well as just the sex.
You're going to have a hard time feeling intimate with someone who you are feeling resentful against. I think once you figure out how you want to move forward you're going to have to deal with it. The past hurts will have to be forgiven and maybe not forgotten. After a long time struggling with the issue of sex and relationship it's going to be hard to get back on track with out a plan.
Right now your wife is showing a willingness to change the way that she is in the relationship she's showing this through her willingness to have sex. I think you should take that willingness as an opportunity to get more out of this than just sex. What do you want to get other than just sex? (a sandwich isn't a good answer)
I'm not sure if you're totally ready to recommit yourself in this marriage but I think that it's important to really think how the relationship you want will look, feel and how you can see getting there. You also should try to open up to your wife about how your feeling when you get what you want figured out.
