The more partners a woman has had, the less likely she ends up with her first choice.
Most women can sleep with an 8-10 man if they try, but they can't keep him because to him she is casual or a side chick.
She holds out this idea that she can get that level of man long term
'but she can't and by early 30s she starts to realize it's not going to happen. But by then men start to see her as less attractive due to age / lower fertility and her options decrease even more.
So she either settles and is less happy or stays single and you get this chart.
It's such a messed up system that every society since the Bronze Age instituted arranged marriages to avoid this.
Excess male sex drive was absorbed by prostitutes, which were between 3-5% of the female population.
It worked sooo much better.