As Outline reporter Rebecca Stoner explains, "the claim that men “naturally” prefer younger women is an assertion of power cloaked in the language of evolutionary psychology. It implies that a woman’s accomplishments, power, money, intelligence, and ambition are, at best, secondary commodities on the marriage market. Men, in this formulation, only get better with age."
Both men and women deteriorate with age. Studies show that both find people in their twenties objectively more attractive than during other points in their lives. That the idea has become so gendered, reducing the value of women to their appearance, is where we should be focusing attention.
Using this defence to excuse infidelity suggests that men cannot stop themselves from having a sexual relationships with any younger woman that they see. This is untrue.
There is also a further layer to the OKCupid study. As Business Insider reporter Pamela Engel notes, Rudder also found that "But there's another layer to this data. Although men at every age seem to be attracted to very young women, they most often message women who are closer to their own age." This exposes the difference between attraction and intent to act on that attraction. The two are not obviously linked.
Finally, were this the conclusive reason that people cheat, infidelity would exclusively take place between older men and younger women. This is not the case.