Eins + Eins = Drei(1927)

Paul and Peter share a garret flat. Paul is smitten with Anni, but her father forbids their match. Then Paul inherits a fortune—on one condition: he mustn’t marry “a girl.” Desperate, they scheme a sham marriage: Peter weds Anni so she’s no longer “a girl,” allowing Paul to claim his inheritance. Jealous at first, Paul watches as Peter and Anni wed, until, after their quick divorce, Paul finally wins Anni’s hand for real.