I have a business partner question?

I have two business partners and we own a salon. All the other workers sublet their station from us. We recently decided to rearrange our reception area.One of our renters decided she did not like it because her little old ladies can't have their hen parties by dragging our chairs aroiund. We moved the chairs for a better retail flow the chairs were a hindrance because they were being dragged around. This renter caused so much fuss about it one of my partners moved the chairs back without consulting with us first which in our contract is forbidden. I am furious with her for doing this without talking to us first. It is like she involves everyone in the shop with our decisions except her partners.-I confronted her about this issue now she says she is quitting and going to work somewhere else which could leave us in a finacial mess. She says we can buy her out or not it does not matter excuse me u want to leave us with all the bills and get paid I don't think so. What to do?