As he's not leaving his wife I decided I could no longer be faithful to a man not faithful to me. trouble is its hard getting shallow time with man nice enough to have shallow time with, if you see what I mean. I have limited but positive experience of casual sex when single, but feels a bit strange being open to it when I'm a bit on the side and love the man in question...
It's not 'tit for tat', just an uneasiness on being second fiddle for all practical purposes.