As a polyamorous person, I don't support cheating because it involves lying and dishonesty, but I do think that there is significant evidence that sexual monogamy is a rather recent human expectation - even though pair bonding is quite ancient.

Gorillas (who engage in mate competition before coitus) have tiny testes and penises. Animals that engage in sperm competition like chimps have larger penises and testicles relative to body size. Humans are somewhere in the middle but certainly seem to lean more towards the sperm competition side.

I'll look forward to checking out the Science Daily piece.