Too bad this thread has drifted off the topic somewhat. I found the first few pages interesting. I have a SB who I first saw when she was escorting. Neither of us knew there were hard and fast "rules" for what a SB or SD does so we felt our way, literally and figuratively. I find some of the opinions here describe our arrangement while others do not.
Anyone here play pinochle? I enjoy the game and have played it all across the world. Every local has local variants of the rules. I learned very quickly that I needed to clarify the house rules every time I sat down at the table, even though I had a copy of Hoyle with me. But whatever the local rules, the game was essentially the same.
So I see it with a SB/SD relationship. I provide her an allowance, I bought her a car when her old one died, I have opened doors and do other things to assist with her career. In exchange she does things for me. Clocks and fees are never a consideration, nor are X meetings a week or month. What we do on a given meeting depends only on what we decide to do. We talk a few times a week or more. She will text me and ask my opinion on whether the blue blouse or the red one looks better. I will call her when I need someone to talk me out of strangling someone at work. We are some mix of friends, lovers, benefactor, protege, and likely a few more things. We travel often as I enjoy taking her with me on business trips when her schedule allows. We spend plenty of time together, but when we are apart we have our own lives. The arrangement has been mutually beneficial for over eight years and changes all the time. Part of the time she was escorting, part of the time she was a full time student, and now she has a career she is developing. What she did away from me did not impact what we did when we were together, other than it influenced the topics we might talk about. The time she was a full time student was more trying on our relationship much more than when she was escorting because she put so much time into her studies. I find it humorous that some of the people who expect a SB to be exclusive are themselves not.
When someone can show me the agreed upon binding definition of a SB or SD I might feel differently, but until then I am of the mind that each such arrangement is largely what the two people decide works for them. Or if the "official" decision becomes too onerous I'll just go back to calling her my mistress. People never seemed so fixated with defining that term.