Personally, I don't play with other people's toys - and would never knowingly make a play for someone-else's partner - whether they were a friend or not - but that's just me living a quiet life.
I may play with other peoples toys, but I have never entered into a realationship with an attached person in my life! NSA for me is exactly that, NO STRINGS ATTACHED, it is not for me to judge why a married person is swinging alone.
I talk to many people who are in relationships, and I wouldn't dream of asking them their reasons for being here, and I will always stand up for those who are honest enough to disclose they are attached,..
Interesting on this site how many grown single men,run away when you ask them why they can't accomodate!