Most people only have one partner. The reason is time. To keep several boyfriends a woman (or man) would need a lot of free time and for the boyfriends/girlfriends to not be aware it is even more complicated. And men are way less likely to be ok with that. So the likeness of those women with "several boyfriends" to be "a lot" is not high. For example: do you really think that if a woman says that she is going out on a Tuesday her boyfriend won't suspect something? Or if you are dating someone that never wants to see you on saturday that it won't be weird?

A different thing is "one night stands". But women are looked down for having those and it might even be unsafe. So also less common in women than in men.

It seems to me that you want to believe some myths about "how easy women have it" without taking a real look at what couples look like. And the regular people lives. Most of our time is spend on regular work day and usually women have even less free time because they are expected to do most of the domestic chores. With that in mind, several boyfriends? That is fantasy at its finest. XD