Given the following context:

Meek California Fidelity Trust teller Johnny Dalton asks his boss J. L. McKissack for a raise so he can marry fellow teller Mildred "Mibs" Goodhue. Though Johnny is turned down, Mibs wants to get married anyway. Emile J. Keck, a friend and waiter at an Italian restaurant they frequent, also urges Johnny to take a chance, even facetiously suggesting he rob the bank where he works. When he insists on waiting, Mibs storms out.
While returning to work, Johnny intervenes when he spots two men beating up a third in an alley. The victim, "Hot Horse" Harris, turns out to be a bookie. To show his gratitude, Harris gives a stunned Johnny $1000, but Johnny refuses to accept it. To make it easier, Harris changes it to a "loan", then promptly bets the entire amount on a sure thing in a fixed race, making sure to place the bet at the bookie joint run by his competitor (the one who had him beaten up). From the winnings, Harris takes back the loan, and Johnny is left with $5000. Harris then makes two more bets for Johnny, both winners. Johnny now has won $60,000. Harris only has $40,000 on hand, so he tells Johnny he will send him the rest later. Johnny rushes off to share the good news with Emile, but Emile believes he took his advice about bank robbery.
As it turns out, the bank's auditors have discovered that there is $75,000 missing. Fearing that he will be suspected of the crime, Johnny enlists Emile's help in hiding the money. When he tells Mibs about his windfall, she does not believe his story either. She finds $20,000, the remainder of what Harris owes Johnny, and goes to see Bob Pulsifer, Jr., the lazy, lecherous son of the bank's founder. She offers it to him on condition that he not inform the police about Johnny, but he telephones them anyway.

answer the following question:

Who does Mibs storm out on? 

Johnny Dalton