I think your theory hinges too much on the individual choice assumption (i.e. people making choices consistent with their individual preference system). My own explanation would emphasize the role of social values and expectation in guiding individual behavior. That is to say, people do what they think would make them popular or accepted by others, what they perceive as the conventionally accepted "right thing to do."
Some people are more conventional than others, which is their cognitive mind set rather than an individual choice. There people are also more likely to go with conventional expectations. Thus, women with more conventional mind sets are more likely to opt for more conventional gender roles ("feminine" women and "manly" men) and choose their mates or partners based on how well they embody these conventional gender roles.
Of course. "conventional" is relative to one's reference group rather than mainstream society. People can be conventional in non-conventional settings e.g. gang members (non-conventional group) can be very conventional and conformist by the gang standards.
wojtek