A lot of people end up getting married more out of expectation than out of passion for each other, but if your options have ever been, 'We either get married or break up,' be careful. Marriage should be a new addition you add to the house that is your relationship, not the structure you impose on the house once it's already built.
Often, when cheating happens, we rush to place blame solely on one person - either the person who did the cheating, or more insidiously, if it happened to us, we blame ourselves for not being 'good enough' to keep them around. But putting it all on one person doesn't paint the entire picture.
In my experience as a therapist and as a friend, it seems that the majority of the breakup resources available are for women and not men. Women, who tend to be more vocal about their emotional struggles, are the squeaky wheel that gets the grease from friends, from online communities, from books, and from therapeutic approaches.