In the simplest form I can put it is .................CONQUEST
I believe it is in a man a drive to conquer. To overcome certain situations, for instance, we are driven for Power, to overcome, to compete and win any and all circumstances put before us. When we are unable to overcome, it makes us feel less than a man on the individual scale. Here is the definition of conquest :
con·quest,
noun
1. the act or state of conquering or the state of being conquered; vanquishment.
2. the winning of favor, affection, love, etc.: the conquest of Antony by Cleopatra.
3.a person whose favor, affection, etc., has been won: He's another one of her conquests.
4. anything acquired by conquering, as a nation, a territory, or spoils

This goes for women to but I believe it is the core of a man's drive.
NUMBER 2. MAY BE OF INTEREST TO THE WOMEN WHO HAVE BEEN CHEATED ON. But just remember, This is about MOST men NOT ALL MEN.
What do you think is the core drive of men ?