"Interference with business relationship" claim requires wrongful act

Michael Doyle was sued on a commercial loan guarantee and attempted to pursue a counter-claim against the Mercantile Bank of Michigan.  Mercantile's predecessor had loaned money to Doyle to build a commercial building in Okemos, and it had also loaned money to the building's largest tenant.  When the tenant defaulted on its note, Mercantile essentially shut it down by pursuing legal creditor's remedies, and wiped out a primary source of income to the building.  Doyle argued that Mercantile's aggressive pursuit of creditor remedies wrongfully caused his default on the mortgage on the building.