My question involves landlord-tenant law in the State of: Tennessee
I currently am on a month to month lease at an apartment complex with my roommate. However, I have been living with my girlfriend for a little over 4 months. Seven weeks ago my girlfriend and I decided to officially move in together. I told my roommate six weeks ago (the week of Oct. 14th) that I was going to be moving out at the end of November. He said he was thinking about moving out as well, but when I asked him what his plans were he did not have any. 4 weeks ago, I asked my roommate if I could move my stuff this upcoming weekend (Dec 7), to which he agreed. He also said he was still thinking about moving out but did not know when.
This week I talked with management and they said I need to sign a roommate release form and he needs to sign it too. Now my roommate is refusing to sign it. Management has said that my only option is to give them a 30 day notice and I would have to pay another month's rent. He claims that he too is moving out, but has not given his 30 day notice.
My roommate and I have always gotten along, and I never thought he would refuse to sign a release form. Lesson learned is I should have given a written notice to management before this week.
My question is more of a hypothetical with a high probability of coming true. By refusing to sign the release, he has forced me into paying another month's rent and give a 30 day notice to management. He has also said that he is moving out as well, but cannot give me a definitive date or plan. If he stays at the apartment after my lease is terminated, is there any way I can legally get my rent back for the month of December based on a verbal agreement I gave him over 6 weeks ago?

