I agree with Scott that dying from get separated is a rare event. Most likely she will carry on and try to approach your male quaker.
Nevertheless, if you intend to breed them, it might not be a good idea to buy a female that is already bonded with another bird, to pair with your single bird. She might not like the new companion because she miss her previous mate. There are species that can switch mates quite easy, other not so.
Budgies are kind of easy to remate, lovebirds just taught me that some females can never settle with another mate after they have chose a partner and got separated. I don´t know about quakers, if you find out please let me know.