In the western world, we as a society have normalized that young women should be able to experiment and have fun in their youth without being stigmatized. In the spirit of equality, shouldn't we normalize the same for the middle aged men who end up in relationships with those women when the later decides it's "time to settle down" (which is usually past 30s, when their prime is past)? Why shouldn't the middle aged man, who at this time in his life has the resources to do so, not have fun with younger women, in the same way the now middle aged woman used to "experiment" and "have fun" in her youth?

In my view, the two attitudes are edges of the same sword and we as a society should perceive them in the same way. If you minmax your way through life, it's only fair to expect other people to do the same to / with you. And although I believe women can (and should) be able to decide how to live their life, the associated trade-offs for those decisions should be made more visible (subject at which we're currently doing a terrible job). A woman should expect a man to be loyal to her when she gets old only if she spent her youth with the same man.