What is wife material?

A friend of mine was told that in order to be wife material, she probably should not be out every weekend.  Apparently, single women who go out too much can send the wrong message?  I suppose the idea is that you have to actually show that you are ready to settle down.

I don’t ever hear about men being told this, though.  Are men expected to show they are husband material?  When you are single, do you think people are constantly determining your wife or husband potential in this way?

If wife or husband material is a thing, what do you consider someone who was?