You will find a lot more instances of men cheating on their partner, but I know this number is not as skewed as it once was. In my opinion, women are now cheating at a rate close to men. They do not flaunt it as many cheating men do, hence they are not getting caught as much. The sites such as Ashley Madison are reporting to have nearly as much women members as men. I think that is a true snapshot of what is really going on.
I get a lot of emails now from just as much men that that have been cheated on as women.
So to answer your question, I will say I think men cheat slightly more than women. They just caught a whole lot more.