My District Manager says I can't get a promotion unless I stop hanging out with a certain manager.?

I am friends with a manager that works in another location over 1 hour away from the location that I work at. My DM told me today that I can not get a promotion unless I stop hanging with this other manager because we can get in trouble for hanging out. I looked through the employee handbook and it said nothing so I asked my DM about the policy and procedure and if I could get it in writing. She said no because its not a policy and procedure but its a suggestion. Me and my friend never talk about work and we never call each other at work or interfere with each other at work. What should I do about this? Can my DM stop me from getting promoted because of what I do in my personal life? Please someone give me some advice... I have worked with this company over a year and would like to continue on working their but not at the expense of my friends and family.