For the same reasons men cheat boredom, insecurity, self loathing, lack of will power, lack of self knowledge and just plain evil. It's almost always reflective of the character. You will find that people who cheat and justify it will also have no problem with stealing and justifying it as well.
Don't cry, don't regret and don't blame
Weak find the whip, willing find freedom
Towards the sun, carry your name
In warm hands you are given
Ask the wind for the way
Uncertainty's gone, your path will unravel
Accept all as it is and do not blame
God or the Devil
~Born to Live - Mavrik~