Commitment

I found out someone I thought of as a friend has had a dalliance with a married man. It wasn't a one off meeting, it lasted for over a year. She can't see why anyone would be upset by this. If his wife didn't know it was going on then it was her own fault. If my 'friend' thought it was acceptable why didn't she tell anyone why it was going on. You think you know someone. She is offended I was offended......