fraud
The fake marriage to Stannie, did not actually relieve mother Peep of her debt to Barnaby, (everyone celebrated it so, but they were wrong,) and indeed could have resulted in Barnaby making a claim before the King, with Mother Peep being banished to Bogey land for defrauding him in order to renege on a debt.
With Tom Tom, for pig-napping, the boys for burglary and fraud, Mother Peep for debt, and no one to protect or provide for her, Bo-Peep would have been left destitute, and desperate.
She would have married Barnaby as a last resort, but gladly to bury her sorrows as a tragic yet beautiful wife. ("married to man with hands as cold as ice...")