The correct answer to this question is Astrid Menks. Monks came into Warren Buffet's life after being introduced to him by his first wife, Susan Buffet. At the time, Menks was a waitress, and when Susan met her, she believed she would be the perfect companion for Warren to have.
Eventually, Menks went on to move into the Buffet home. All three of them had a unique relationship and would often be seen in public together. Along with that, they would sign their cards with signatures from all three of them. After Susan's death, Menks went on to formally marry Buffet three years later.
Astrid Menks is a Latvian American philanthropist and former cocktail waitress. She had relocated to the United States in the hopes of prosperity, and she found it with Warren. In the 1970s, Astrid was working as a waitress in a cocktail bar when Warren's wife introduced the two of them.
She was also working at the same cocktail bar as Astrid. Susan felt that Astrid was the right candidate for being a female companion to Warren. He never divorced his first wife, but he had a relationship with Astrid.