I've had it happen before. I was taking private music lessons with a guy I've known for years. He's a musical genius and can play anything. He started offering lessons for extra cash. He was divorced with two kids (I was friends with his ex too, they were both really good people) and started dating this mom with a toddler aged kid. She would always turn up during lessons with the brat in tow,"checking up" on him. Here I am paying him for my time and here she is week after week interrupting that time. I had no designs on him, and he had none on me. It was strictly business, I was there to learn to play music and he was my teacher. I stopped going to lessons because the last week she pulled it, she wasted like 20 minutes of my hour lesson. I never met somebody so insecure in my life, and the thing is, she was quite an attractive lady. Anyway, they didn't last too long, I'm sure he got tired of her unfounded jealousy and control issues. Maybe he was cheating on her, I don't know/don't care, but certainly not with me.