They want to get impregnated by Chad,
but they also want an oofie-doofie betabuxxer wimp they can control and enslave and use him for resources, stability, comfort, emotional tamponage, security, and to flex their own ego -- foids derive immense pleasure in exploiting and deceiving beta males, foids truly enjoy using men's emotional weakness ("love") to manipulate them, and also foids enjoy repeatedly cucking their beta providers all through the duration of their association.
In fact, although foids enjoy sex with Chad, the quality of the sex she has with Chad becomes much better if the foid is also cucking her beta partner -- that is why foids feel the need to obtain beta partners, to cuck them with Chad and enjoy sex with Chad even more, knowing that once they get pregnant, they already have a fool in love to support her.
While the greatest pleasure of men is creampie, the greatest pleasure of foids is deceiving men.
Chad gives foids good sex, but won't stick around to be deceived.
Foids can only obtain the ultimate pleasure of their lives by cucking her beta partner with a Chad.