Just after Marlene finished The Spoilers, Gabin went off to make a bad picture called Moontide, giving Marlene time to rest and recuperate from the rigors of their relationship...

Gabin dodged the nosy next-door neighbor, who appeared each afternoon at four in a floppy straw hat and sunglasses. The neighbor displayed fanatic devotion to the shrubbery separating the properties, creeping along and peering through for a glimpse of grass she suspected was greener than her own. Her lope was vaguely familiar, but horticulture was a previously unsuspected passion of the female Peeping Tom, whom he finally realized was Greta Garbo. 

Gabin and Dietrich

Marlene, never shy about nude swimming and sunbathing, seemed unperturbed by Garbo's spying, but Gabin was. He was jealous. He was jealous of Marlene's work... Gabin went a little insane, too. He beat her. The "though guy" persona was no pose; he used his fist when jealousy proved overwhelming. When she bought lingerie, he wanted to know for whom.

When she went to the grocery for the makings of a pot-au-feu, he was certain it was an alibi for a stew of another sort. Her men friends were potential or past alumni, her women friends might belong to the Sewing circle. Gabin was simply uncontrollably jealous.  She was amazing, puzzling, provocative...  Always seductively perfumed.