In all honesty I don't believe there are 10 reasons why men cheat. In fact I believe both women and men cheat for the same reasons.
The goal of any cheater is to (hold onto all that is good) in their primary relationship while addressing their other needs or desires on the side. (That's pretty much it!)
Having said that I believe there are 3 basic types of cheaters.
1. The Incessant Cheater
This individual has no intention of honoring any vow or promise they make. He or she is always looking for the next thrill or something "new". In fact they probably have never been faithful in any relationship. Think in terms of "Relationship ADD". They get bored very easy. Generally speaking they have magnetic personalities. Their motto is "Variety is the spice of life." Occasionally they'll enter into relationships if pressured or they feel it's required. But it's not who they are.
2. The Unbelievable Opportunity Cheater
This person actually intended to be faithful and is not "looking " to betray their partner. They give into temptation when an "unbelievable opportunity" presents itself. A momentary lapse in judgment leads them to do something they later regret and feel guilty about. It may be they had a shot to be with someone "out of their league" or a person they've secretly admired came onto them! "Once in a lifetime."
3. The Discontented Cheater
This person believed they found their soul mate and never dreamed they'd be considering cheating. Unlike The Incessant and The Unbelievable Opportunity Cheater, The Discontented Cheater feels as though his/her partner is (forcing) them to "seek other options" outside of their relationship. It's not a stretch for them to feel “justified” in seeking other ways to fill a need that is not being met.
The first thing everyone says is they should have broke up or gotten divorced if they were unhappy. Again I remind you the cheater's goal is to hold onto the "good parts" of the relationship. They also don't believe they will get caught!
Ultimately if someone cheats on us we (really) don't care why! It's a rhetorical or reflex question. We're not seeking any "understanding" and there is nothing our mate could say that would make us (feel better) about it. Why ask why? :-)