"We like having power-equal relationships, because we think it more moral, because we encourage sexual partners to be companions and friends rather than sticking to separate social spheres, and because it has become more valuable to have a partner who can help you socially and earn money than to have a fertile one."

Who is "we"? Power and sex have deep links. Sexual attraction often does not follow modern egalitarian norms, or indeed norms at any part of history (this is famously exploited in romantic plots in books/movies/tv shows, and similarly frequently observed in practice). Sexuality is ancient, predates morality (and social animals in general), and is often amoral and even cruel. Sex and political correctness do not really overlap.

"Older women's interest would be to encourage woman-boy relationships rather than discourage man-girl ones."

This statement assumes genders experience physical attraction in "symmetric" ways. It is not obvious why this should be so, and there is some evidence it is not.