NC just incase..
Two people who are already in relationships have been meeting for sex. The woman of the two is the one that I know personally.
When talking about it she's of the opinion that it's not an 'affair' per se as it's just about sex and nothing more, any intimacy is reserved for the bedroom and they're not in constant contact and neither of them have caught feelings for one another.
AIBU to think of course it's a bloody affair.. is it not?!
What's your definition of an affair?