Time is on your side
That is why pretty much every really patriarchal society, ever, from the Babylonians to the Sumerians to the Spartans and Romans and Byzantines, right on down to the Victorians, put such a strong emphasis on the idea of women giving birth to multiple sons. This is still true today in India and China.
A beautiful, youthful, fertile woman in her early twenties can have her pick of the men that she surveys. If she was not brought up in a degenerate and destructive culture (like, say, almost the entirety of the modern Western world), then she might choose to spend her resources of youth, beauty, and fertility carefully and wisely upon a very small number of possible partners.
And if she is truly sensible and capable of reining in her worst instincts, she will commit to one of them for as long as is humanly feasible.
If, however, she is the typically deluded Western female, she will spend her youth screwing her way through a football team's worth of men before suddenly and abruptly waking up at around 33 or so and realising that her freedom comes at a terrible price.
And if she ends up in her mid-thirties, childless and either single or involved in complicated relationships, then her future is pretty dim.
A childless woman in her mid-thirties, with a long history of failed relationships behind her, is simply not worth all that much in reproductive terms.