What an interesting topic. My children's father used to try the same type of stuff with me. I stopped asking about the phone numbers and instead would change the numbers without him knowing. I would cleverly make a 3 into an 8 etc. Now of course that is not the answer, but it kept things fun for me. When I was doing this, I had already made the decision that I was eventually leaving this man! But until I had the resources to do so, I wanted to have a little fun. I agree with the earlier posting that trust is the foundation for a good relationship. How would your man feel if you were walking around with some man's phone number? How would he feel if the shoe is on the other foot? If her cannot respect your feelings after you have clearly explained them to him, then you need to consider finding someone who will. I put up with too much crap and got a disease from it----he says they are just friends---yeah right! Then ask to meet them!