Sex with your partner should never be a reward for what they buy you. Maybe I am totally alone on this, I don't think so, but, sex should be something you want to give each other, out of desire and hopefully love, not do this and you'll get it mister or vice versa. Sounds like the barter system to me.
As a man, I totally agree with this, but unfortunately, most women do not. It's sad, but true. Just talk to the guys you work with and see how this is a fact of life for many of them. Too many women use sex as a negotiation tool. My wife has been guilty of it from time to time, but she's really not that bad compared to some previous relationships I've had. When she does that kind of thing to me, I try to do the same thing to her so she can experience how stupid and silly it sounds comming from me. (Besides, I'm kinda twisted, and I like to get on my wife's nerves by imitating things she does). If you have to trade goods and/or services with your spouse in exchange for sex, aren't they really a prostitute? What's the difference? You're right, sweetstuff. It should be different. It should be about love and about wanting to please your partner, not about personal gain or as a reward for stuff they buy you.