It's a matter of co-dependency.
It's well documented. There are plenty of books about that.
Co-dependents are attracted to narcissists.
The more dependent a person is, the more this person is attracted to very narcissistic people.
Very often, because of the way they are raised, co-dependents are women who are brain washed from baby-hood to wait - wait, that's the key word - for a prince charming to make them happy forever; they are taught to take care of their nails and carry purses.
Young boys on the other side, are taught to do things, to be independent, to be the ones who bring the bacon home.
I am sure you and your sister were raised that way.
I asked you once, and you did not answer.
Could you answer?

Now, once co-dependency is deeply burned in the circuits of the brain, it's not easy to get rid of it. First, a woman has to realize that she has the Cinderella Syndrome (that's one name for it). And then she needs a program, and ideally a network of friends, to get out of it, and it takes years and years. If she is in a relationship with a narcissist, she would not want to get rid of the co-dependency because as soon as she improves, the guy will feel threatened by her autonomy. In order not to lose the guy, she will chose to stay that way, Meanwhile, she will raise her daughters to be like her, co-dependent. It's a multi-generational pattern. Can you see how it works?