Under the law, a partner owes a duty of care and loyalty to the partnership and the other partners. The duty of loyalty means partners cannot compete or conduct themselves in a way that is detrimental to the partnership.
Under the duty of care, the partner must complete their obligations in good faith and in a manner they reasonably believe to be in the partnership’s best interest. Thus, if your business partner disappears after you start the business, you may have a claim against them.
However, you may have chosen to vary these duties in your partnership agreement. In that case, you are bound by the terms of your agreement.