We men have the biological instinct of impregnating as many women in fertile age as possible in order to have abundant offspring and pass our genes to the next generation at the least cost. This is the reason by which we cheat.

Women in serious relationships cheat on their partners with another man physically more attractive in order to get pregnant with genes of better quality. A woman gets the best of both worlds in this way: the financial security which her formal bf or husband provides her (beta provider) and the sexual excitement and higher quality genes that her lover (alpha chad) offers her.