I'm sorry for your situation. I myself need a very positive partner, instead of telling me what I'm doing wrong every single time....let's focus on just how to make it better. You help each other, not just one side badgering the other. Everyone practices differently, if this is as important to you as it is to me then the partnership won't last long. If you can ignore it and tune out the negativity then maybe you can make it last a year or more..but ask yourself if you can do it and if it is worth it? Of course another option is to just practice in front of a coach. Just let him observe and give his comments. Not on the quality of dancing but on the effectiveness of your practice. What do you think?