I am curious why you think your daughters happy future can only happen with a partner?
My DD decided very young that she was not suited to being in a partnership or having children. She is coming up to 50 now and has made a happy and independent life for herself. She has her own home and plenty of friends, male and female, has been able to concentrate on her career without needing to juggle it with childcare.
I have several female friends who have never married and, now heading for 80, and live independent social lives, with close family contacts with siblings and nieces and nephews.
It is time we stopped assuming that a relationship was the be all and end all of life and you cannot be happy and secure without one.
Perhaps, if you encouraged your daughters to realise that having a partner is not a sign of success, or an answer to life's problems, they have surely discovered that by now, and that, while they would prefer a partner, they should try seeing the future in terms of being proud and successful single women.