Is Lindsay Lohan engaged to Samantha Ronson?

The actress -- who told Us Weekly she was "so alone" after her April split from her DJ girlfriend -- was spotted in London with a diamond ring on her left hand (where engagement rings are usually worn, although she had it on her third finger instead of ring finger).

Check out more photos of star engagement rings.

The pair, who dated for about two years, caught a flight to L.A. together at London's Heathrow Airport Monday. Lohan was cryptic on her Twitter page. "Leaving London but but with my favorite favorite!!!-travel buddy & great news to share!! Maybe…." she wrote.

Relive Lindsay and Sam's most romantic moments.

Getting married would be a 180 for the couple: According to Britain's Daily Mail, they stayed at separate hotels, and Ronson avoided Lohan on the club scene.

See all of Lindsay's loves over the years.

Meanwhile, an air date was announced for Lohan's flick Labor Pains, in which she fakes her pregnancy to save her job at a publishing company. The direct-to-TV movie will be broadcast Sunday, July 19 on ABC Family.