Have a friendly talk to him about this matter, and agree upon some parameters as to what can be run through the business. I know of a partnership in which one partner is running every personal expense possible through the partnership, then both partners divvy up the net income 50/50. In reality, it's more like 65/35, and the partnership is dissolving the hard way due to the refusal of the 65 partner to change his ways.

BTW, I'm hobbling along with a iPhone 4S, hint, hint...