2 business partnership questions for 2 different businesses

1. I have one business with a business partner - next month we are forming out partnership agreement after many years. We agree on almost everything, but we are not sure how it works when one partner wants to leave, and there is sales tax/ excise tax that has not been paid? 2. My other business is new - forming partnership agreement for that as well, and we have been in business for 3 months. My business partner has another business, and has been up front with me with telling me this is more secondary, and not his main priority. I am trying to figure out what is fair with pay/ownership because I am frustrated before even fully launching.