26 Jul This is why a man is always desiring other women. (SCHOPENHAUER)
That an absolutely generic instinct is the foundation of all love of sex may be confirmed by a closer analysis of the subject — an analysis which can hardly be avoided. In the first place, a man in love is by nature inclined to be inconstant, while a woman constant. A man’s love perceptibly decreases after a certain period; almost every other woman charms him more than the one he already possesses; he longs for change: while a woman’s love increases from the very moment it is returned. This is because nature aims at the preservation of the species, and consequently at as great an increase in it as possible.
This is why a man is always desiring other women, while a woman always clings to one man; for nature compels her intuitively and unconsciously to take care of the supporter and protector of the future offspring. For this reason conjugal fidelity is artificial with the man but natural to a woman. Hence a woman’s infidelity, looked at objectively on account of the consequences, and subjectively on account of its unnaturalness, is much more unpardonable than a man’s.
Metaphysics of Love, Essays of Schopenhauer