They had an affair during the filming of Whipsaw in 1935 and in 1936 during Libeled Lady. At the beginning, In her autobiography, Loy said Tracy had chased and harassed her. James Fisher in Spencer Tracy's biography in 1994 said about a rumor. Christopher Andersen (Tracy - Hepburn affair in 1998), revealed that Spencer Tracy and Myrna Loy had a serious affair during Whipsaw and resumed their relation a year later, 1936, when they co-starred in Libeled Lady. Andrew Scott Berg (in Kate remembered in 2003) and Jane Ellen Wayne (The leading men of MGM and the golden girls of MGM) had also written that. To Garson Kanin, Tracy said that he would prefered make much films with her instead of Katharine Hepburn. He was deeply in love with Myrna Loy since he saw her as Mrs Nora Charles in the The Thin man movies. She didn't mentionned this romance in her autobiography, but few index suggests that she was romantically linked with him (she called him darling in her book). They managed to keep secret for not damage her reputation. For that, Tracy invented stories. During summer 1936, the two co-starred in Libeled Lady with Jean Harlow and William Powell and had a torrid affair. For not catch attention of tabloids and crews, he joked that Loy's marriage with Arthur Hornblow Jr has broken his heart. He shouted "I hate Hornblow" and "I am jilted by Loy" at table in the studio commissary, reserved for men. They never knew while Jean Harlow and William Powell shooted a scene - they were lovers in real life - he was secretly in his private dressing-room with her, repeating a scene, an afternoon. He
drunked and had sex with Myrna Loy (He knew it was impossible to get Loy pregnant because she was infertile). During Test Pilot, Once again they were discreetly involved despite Clark Gable who tried to seduce her in 1933. A few years laters, she visited Spencer Tracy who played in Tortillat Flat (1942). He came in her room in St.Regis Hotel for reveals to her he had "found a woman" about Katharine Hepburn with whom he played in the women of the year. Loy said he had drunked, was nervous and smashed a cup. Despite an argument, he bedded Myrna Loy before to leave her room. Later, she wanted to make The sea of Grass with Tracy and was ready to resume her affair with him. Tracy wanted her but MGM, finally took Katharine Hepburn.