This is slightly unrelated but somewhat proves the point.
Someone I used to know bought his girlfriend an xbox 360 for Christmas, this was back when they released so it was a pretty big present to give her, he also bought her some games and shit, easily cost a couple of hundred. He gave her the present and in return she immediately gave him a blowjob, awhile later he asked if she'd got him anything since he'd been hinting at some random thing for awhile. She said, with a straight face and utter sincerity that the blowjob WAS his present. According to him to flipped his shit, started yelling and getting really in her face about it. She started crying and left the room...10 minutes later she came back into the room naked and started trying to fuck him.
Women are emotional manipulators that are hardly even in control of their own emotional state. They are less reliable than children and trying to bring any rationale to their actions is a pointless pursuit.