According to FemaleFirst, Miller met the married millionaire through an ex-boyfriend Matthew Rhys, who worked with Getty on the television series, Brothers and Sisters.
During the time the actress was filming G.I. Joe, she had a dinner date with Getty in Los Angeles, but their relationship became serious only after she split with Ifans earlier this month.
A source revealed, "Sienna has known Balthazar for a while and they’ve spent more time together over the last four months. They became closer after spending time dining with friends at the Chateau Marmont in March and April. When Sienna realised she had feelings for Balthazar, she ended her relationship with Rhys over the phone. She wanted to do the right thing before things really happened between her and Balthazar. Since then things have quickly gotten very intense between them."