There is drama over infidelity that gets caught.
There is drama over infidelity that is suspected; rightly or wrongly; but never caught.
Beyond infidelity concerns, there is drama over those who feel left out of sex and dating altogether. Mostly men / boys (more of them claim than women / girls to identify as single, suggesting either polyamory or respondent dishonesty) but not exclusively. Even women have supposedly been rejected, at least from monogamous relationships. I wasn't there, nor have both sides of the story, so I would never claim to know.
But in case it's true, ask yourself this; if there were no expectation of monogamy in the first place, would these women have been just as likely to be rejected from casual sex in that circumstance as from monogamous relationships now? Would that not double as a means of cutting down on drama over infidelity, by giving everyone expectations that are easier to meet?
The average male's sex drive is so intense, so extremely overwhelming against all capacity for rational thought, that in their teen years most boys risk impoverishing themselves for life; much less their female sex partners; by having sex before they could afford children, with nothing to go on but her word of knowing what she would do if she fell pregnant. (Obviously mine is milder, as evidenced by the fact that I am typing this instead of, let's say, watching pornography.) It is absurd to expect them to go from that to having the self-control to spurn the advances of every would-be mistress, unless you think pollution somehow reduces sex drive that much between one's teen years and one's 20s.
As such, with men/boys not having the self-control to uphold monogamy, it's either up to women or a lost cause. And by the aforementioned "more men/boys claim to be single than women/girls" statistic cited earlier, I'm going to go with monogamy being a lost cause.
So why not just drop the facade, and embrace what our evolutionary cousins, the bonobos, did, by making this sort of thing a group activity instead of a pair bonding one? No more drama over infidelity if you never expected exclusivity in the first place. Fewer reasons for anyone of either sex to feel left out, if people have enough variety of partners to not care about any flaws, be they significant flaws or superficial ones. As well, people would be less complacent about the need to wear protection if they did not have the illusion of a monogamous partner. If people were always wearing protection (with the exception of when procreation was intended, of couse), many STDs could be eradicated in just a few generations.
