Someone else around here said that women have sex when they feel loved, and men feel loved when they have sex. Women feel loved when they don't have to nag their men 1000x to do something that needs to be done, and they demonstrate that love by having sex with you. I don't really know how that qualifies as using sex for manipulation.
On the other hand, I don't know what's up with the "take me here, buy me that"... THAT sounds like more of an issue with the kind of women you choose to date.
Relax... I'll need some information first. Just the basic facts - can you show me where it hurts?