Defined Roles and Responsibilities: Clearly define each partner’s role and responsibilities to avoid overlap and confusion.
If you are a partner in a business you have to strive to remain relevant in that business and in the role you play for the business so that your partner does not start considering doing away with what you offer to the company and taking sole ownership of the business that both of you started together.
In every role you are assigned, stay up-to-date and function in that capacity to the fullest.