I kind of like the idea of a swinging mentor.
My first group sex experiences were with my rock and roll sweetie.
Never really got over it though... 
My first true swinging experiences were oft-discussed with a dear friend from South Texas. Now that I'm thinking about them ...
I sure miss those conversations.
I think a swinging mentor is fine.
Better so if they remain your friends whether or not you have sex with them.
Slutty Wife