I think men are more likely to cheat than women - partly because, in the traditional marriage set up, it has been easier and more socially acceptable for men to have mistresses. Also, traditionally, men were in control of the finances which put them in a position of much more power than their wives.
Tradtionally, the knowledge that a husband had cheated might, possibly, raise a few eyebrows but in general the wife could not afford to get rid of him on the basis of infidelity alone. Apart from leaving her and her children financially worse off, socially it was more acceptable to be married than not. So women just put up with it.
It was traditionally far more risky for a woman to be unfaithful - she risked losing her financial security, security for her children, her reputation and her social status which was quite likely to be bound up with her marriage.
Even today I think there is far more acceptability for male infidelity than female infidelity as there is still a cultural expectation that women should put their children first, whereas it is considered acceptable for a man to put his career (and other needs as well) first.
Things are changing because divorce is now considered socially acceptable and there will be sympathy (rather than scorn) for a woman who dumps an unfaithful husband.
I take issue with the comments about people who cheat being selfish or immature. I think that is far too simplistic. For instance, I think whether you cheat or not has much less to do with morality than people admit. I think is is mostly to do with opportunity, personality and also one's own attitude towards risk.
The alpha male type of personality tends to be one that embraces risk - so if you elect to marry this type of man I think it is possibly naive to imagine that you will be rewarded with lifelong fidelity along with all the other stuff - money, exciting life style etc.
Women innately know this which is why the evolutionary biology stuff makes sense. Eg: have a wild romance with an alpha male type but don't marry him unless you are prepared for the mistresses that come with the package.
If you want lifelong monogamy without any fireworks go for the nurturing, risk-averse man who you know will stick around long enough to raise your children.