This desire to destroy monogamy is often referred to by its practitioners as sex-positive. The idea being that all conceivable (or more likely inconceivable, pun intended) forms of sexual expression should be not only tolerated but celebrated.
I’m afraid I will never understand their root assumption that all other human drives can be misdirected and turned to evil, but somehow the sexual drive, the most powerful of all, can only lead to good.
It is an act of cultural revolution. The Weather Underground too wanted to Smash Monogamy (they engaged in partner swapping/swinging even with members of the same sex and it was wrong to say no to someone).
Free love isn’t free. It’s about smashing the institution of marriage and fidelity.
Maybe it is considered an opiate of the masses (have them distracted always searching for a hookup).
Planned Parenthood is a sex positive proponent. They claim that abstinence ‘doesn’t work’ but dig deeper and you’ll find that they abhor abstinence because it is counter to their worldview. It’s ‘unhealthy’ because it is a denial of sexual desire. On a corporate level, they oppose it because it is bad for business (gotta keep ‘accidents’ happening to keep the money rolling in).
It isn’t about ‘family planning’. Margaret Sanger is on youtube (Pathe News, 1947, UK) demanding ‘no more babies’ for 10 years in Western Europe (no ‘choice’ in the matter, if you can’t have them after the 10 year ban is up, then it sucks being you).
So they want to divorce the sex act from the procreative act. This too smashes the concept of ‘family’ (married or not).