What's the difference between an "EF" and a Mistress?

They can be the same things. EF (Emotional Friend) sounds better. With the word "Mistress" you just automatically ume there is an extra-marital ual fling going on. With EF you don't ume that. It leaves open the possibility that it's just platonic. You need to be careful with the words you use in the M&D section, Harry. There are some people with no sense of humor.