His Brother's Wife(1936)

DON'T ASK ME TO KISS YOU! YOU'RE MY BROTHER'S WIFE!

Epidemiologist Cliff Claybourne falls in love with Rita Wilson in a gambling house. They want to marry but Cliff's brother is convinced Rita is no good and forces Cliff to fulfill his agreement to do research in Africa in exchange for paying gambling debt. Rita, Cliff and brother are furious with each other, but Rita and Cliff are still in love.