The Room star was spotted wearing an engagement ring while hosting U.S. comedy show Saturday Night Live this weekend (7-8May16).

And Brie's representative confirmed to Us Weekly magazine the couple will marry.

A source close to the couple told the publication that Alex, 36, proposed to the 26-year-old Oscar winner during a trip to Tokyo in March (16).

The insider added the actress was keen to start a family with the Phantom Planet frontman.

Alex's band are perhaps best known for their song California, which was used as the theme tune for U.S. TV series The O.C.

He accompanied Brie to the Academy Awards in February (16), and after she won the Best Actress prize for her role she mentioned him in her winner's speech when she thanked her "partner Alex Greenwald. I love you, the whole thing!".

Brie first revealed she was dating Alex back in 2013 when she acknowledged him as her boyfriend after she won the Best Actress gong at New York's Gotham Independent Film Awards for her role in drama Short Term 12.