I appreciate your honesty.
I just think part of really honouring your wife is laying boundaries that give your relationship exclusivity that are just for you and her.
To be open with you, my concern is why on earth would a woman who loves her man and is sexually attracted to him give him permission to "sleep" with another woman, innocent or not. Woman are loyal and territorial creatures, made by God for one on one relationship, something doesn't add up to me
I think you are pushing the boundaries and being disloyal in way
Intimacy in all forms should be exclusive between a married couple, anything else is taking that away, permission or not
And why would a decent woman who respects friendship push a boundary by sleeping with another womans husband? Innocent or not.
This is just my personal view and I do not wish to be disrespectful to you both.
A marriage is not just based on sex but it sure is a solid foundation that God gifted us to enjoy and cherish.
Keep your "friendship" out of the bedroom would be my suggestion and save ALL your intimacy with your wife.
The fact you are asking this question suggests you are not sure if your actions are ok.