The aging of the population and the falling birth rates make young adults more rare( as a porcentage of the total population) so in the more distant future women in their 20's will be more desirable than ever before as they become more scarce ( due to the principle of supply and demand) and since they are at their prime they will still be considered more attractive amd more wanted for dates and relatioships since men are quite visual for physical attraction and dates. Obviously considering that aging reversal technology has not been created and available for most people...

Men will compete pretty badly for the scarcity of beautiful and youthful women to the point that younger women will become extremely picky towards men...