The first and, as of right, the main reason is man's indifference. A woman needs constant attention, warmth and affection that can not always give a man by virtue of his lack of emotion and desire. Therefore, the lady to confront feelings turns them "on the side".
Female infidelity can be triggered not only by the lack of feelings, but their overabundance. In a literal sense, throwing ladylove gifts and attention, the man in the relationship eventually leads to the fact that the woman did not want him. She has no sense to show their hot, sexy and interesting, because a man completely enthralled. The person can not appreciate what he has.
The third reason is the lack of understanding between a man and a woman. Over time, delicate and expensive feelings become bored. In addition, sometimes a man is not willing to discuss the accumulated problems, take any decisions and change. Tired of searching though any compromise, a woman seeking an outlet in the company of another representative of the stronger sex.
Reason Four: woman commits adultery in retaliation for male infidelity. In the arms of her lover woman again feel desirable, sexy and attractive.
Another reason may be hiding in too open and free sexual relations. Swinging, participation of both partners in group sex, flash mob - devalue feelings of loyalty and love, which transcend the cellar.
But the most banal of all causes, is a simple interest. For fun, many women prefer to have both a family and a lover, which, in turn, is considered the norm. And where there is a betrayal, no love, no strength or stability in the relationship.