Scarlet Street (1945)

Chris Cross is a mousy, but trusted bank teller married to a relentless nag. His only joy is the painting he does on weekends - until he accidentally meets beautiful "Kitty". Her boyfriend Johnny convinces her to take him for everything he's got when they mistakenly believe that he is a rich and successful artist. In order to keep her in the style to which she is rapidly becoming accustomed he has to come up with ways to put his hands on ever larger amounts of money. But no matter what he does, it's not enough for Kitty and Johnny, who keep pushing until even they are in over their heads.

IMDb: https://www.imdb.com/title/tt0038057