The 34-year-old star split from the 'Gravity' actor last July after two years of dating, but she's pleased her former lover is now planning to settle down with the British lawyer.
A source told E! News: "She wishes nothing but happiness for anyone she's dated, including George."
The former wrestler has also moved on and is now expecting her first child with her new husband Jared Pobre, whom she married in February, later this year.
The source explained: "Stacy is focused on her life with Jared and enjoying her pregnancy."
However, George's friends believe the Hollywood hunk, who previously swore off marriage, owes a lot to Stacy because she helped him get over his fear of commitment.
A source said previously: "She was one of the first women he's dated who had her own life. She was sweet and had a very good heart, and he was attracted to that."
Meanwhile, the 'Monuments Men' star, who has been dating Amal since last October, popped the question to his beau last month with a seven-carat ring he designed himself after dinner at his Los Angeles home.
George, 52, and Amal, 36, are now planning to marry later this summer.
The source said: "It's only four months away but they want to get married at the end of the summer, in early September, before Amal returns to work."