I have read a decent number of articles saying the a man is actually gaining an evolutionary advantage by having sex on the sly with as many women as possible. Also, that the woman who finds a "better" male specimen does better in evolutionary terms.
That sort of flies in the face of evolutionary thought lending itself to Judeo-Christian morality.
Kindly explain how the theory of gravity might lend itself to Judeo-Christian morality.
A man might...if he were also around to provide for those children and protect them.
Short term advantage: more offspring
Long term disadvantage: fewer offspring reproduce
Add in the fact that having a male unerelated to children in the home leads to mistreatment or death of unrelated offspring (sort of like lions)
Looking at the world-as-it-is I'm guessing that monogamy is on the rise for good sound biological reasons.