I believe that women cannot be monogamous, first they can have sex and give pleasure to many men at the same time for an indefinite period of time, they could have up to 5 at a time and nothing would happen, while men have a maximum of two and very hardly.

On the other hand, they are the ones who decide if they have sex or not since men are always waiting for any opportunity, so it would be selfish and unnatural to confine women's sexuality to a monogamous relationship, they can. have a boyfriend, but they need to have the doors open since they have many options and occasions to have sex, if it were the other way around, men would spend all day fucking. That is difficult to control since it is a daily pressure that they have to deny and fight their sexual impulses out of loyalty.

and finally, women have the duty to select the best possible genes for the species, we should not suppress their reproductive instinct, they should choose the best to procreate, whether it is their boyfriend or not and they should test them and have them inside for this.

This and countless other reasons, women can have partners and get married but that does not mean they are monogamous, they are designed for just the opposite.