Speaking from my past experience with this type of situation, there are a few things that are concerning to me. I am not suggesting embellishment, however, in every single mistress relationship I have had; whereby, I was the Sugar Daddy, it has been my experience that the women have all fallen in love.
It doesn't happen at first. But after 6-8 months of getting to know each other in a professional manner, the I love you's start to ring true. Perhaps it is just me, but when you treat a women with love and respect in that type of relationship, pro or non-pro, they genuinely fall in love with you.
Are you starting to get guilty feelings, and want to "dump" her due to your guilt???