Different ages had different reasons, but in general women indeed weren’t seen as equals.

Also let’s not forget that having multiple wives or concubines was quite popular in parts of the world not Europe and still is for some.

Despite the commodification of women having a long and constant history, I can’t help but doubt monogamy’s exact role in it.

The European modern marriage is still only some centuries old. If i recall the story right, it began with merchant houses trading daughters and signing it as contract on paper/leather. And slowly evolved from there.

The peasantry was far more fluid in their cohabitation arrangements and feuding families needed workers/warriors, so back then there was little time for pleasure and was more a matter of survival.

I believe it was the church that eventually shackled the peasantry in monogamous relationships, for control, puritanism, to attack the nobility or whatever other reasons.

So I don’t see monogamy as a direct assault on women, but rather a welcomed side effect by those who implemented it for other selfish reasons.