There is a very clear standard in the man code. Let me paraphrase sub part b section 13
"One shall not date another persons ex girl if they are:
1. Friends
2. Family
3. Room mates
4. Certain Co-Workers.
There is a loop hole to this standard, If the person had enough respect and consideration to approach the former boy friend and ask and or inform him that he is going to attempt to speak to her. If he were to go about it like a MAN then he would of had a foot to stand on, but since he decided to go about it like a BITCH, not only is he breaking the man code, but the BITCH code as well.