In order to determine whether or not this claim is true, false, or exaggerated/misleading, I first looked at the provided Discreet Investigation & Security article, "Infidelity Statistics: Who Cheats More, Men or Women?" by James Glanville. On the article itself, there's a hyperlink on Glanville's name that takes you directly to Discreet Investigation & Security's "Home" page, stating that the corporation's a private investigation company based in Toronto Canada. As I scrolled down that same page, I found a short bio on Mr. Glanville, describing him as the President and CEO of the company. The blurb goes on to mention that, "... [as] a security consultant, surveillance authority, and clandestine agent, [Glanville's] resume is impressive" (Discreet Investigation & Security). However, despite claiming his excellence in the field, there's no further information listed, such as past academic accomplishments or titles, that credits Glanville's reputability on the topic. Such lack of proof, or in other words, supporting credentials, definitely raised my suspicions when it came to deciding whether or not this claim was truly authentic.
However, in the first few sentences of Glanville's article, he references a 2010-2016 Institute for Family Studies (IFS) survey, that polls men and women on their current, or previous marital status. And, "[according] to the General Social Survey, men are more likely to cheat than women, with 20% of men and 13% of women reporting having sex with someone other than their partner while still married" (Discreet Investigation & Security).
By clicking on the provided embedded link in the primary article, I was taken directly to a 2018 IFS article titled, "Who Cheats More? The Demographics of Infidelity in America" by Wendy Wang, where the statistic's provided. On the IFS website's "About Us" page, Wendy R Wang, Ph.D, is described as the director of IFS and credited with "... regularly [contributing] op-eds and commentary to major media outlets, including The New York Times, The Atlantic, The Wall Street Journal..." (IFS). Therefore, given Wang's impressive list of provided credentials, my opinion on the accuracy of the original claim definitely swayed more so to true rather than false.
Finally, just to be absolutely sure, I looked up the same claim in Google and found the BBC article, "Are Men Really More Unfaithful Than Women?" by Fiona Woods. In the article, Woods further confirms the above statistic, while simultaneously challenging it with the help of Dr. Catherine Mercer, head of analysis at the Nastal study and recurring publisher in the National Institute of Health (NIH). In her argument, Mercer points out a key flaw in previous studies hoping to answer this question, polyamorous/open couples are rarely, if ever acknowledged. Therefore, "this method can give the impression of infidelity where none has occurred" (Dr. Catherine Mercer).
All this to say, I believe that the original claim, that "men cheat more than women" is mostly true, yet too generalized of a statement. As Dr. Mercer notes, marriages exist in multiple different forms, and simply stating that all men cheat on their wives more would be misleading the public through failing to acknowledge the multifaceted experience of marriage.