Alex Pettyfer Engaged To Riley Keough: REPORT

Alex Pettyfer and Riley Keough aren't wasting any time.

Us Weekly reports that the 21-year-old British actor is engaged to Lisa Marie Presley's 22-year-old daughter after dating for only six months.

The couple were spotted on Monday getting lunch in Los Angeles and no one could ignore the giant rock Keough was sporting on her ring finger.

The couple met on the set of the upcoming male stripper movie, "Magic Mike," and were first seen kissing in October.

Pettyfer dated "Glee" star Dianna Agron for almost a year and broke things off in February 2011. The actor earned somewhat of a reputation as a loose cannon when it was reported that Agron was "terrified" of Pettyfer after he threatened her during a phone call. Reps for the actor denied that any threats were made.

Keough has also reportedly dated singer Ryan Cabrera and Jonah Hill.

More celebrity couples:

Loading Slideshow

• Celebrity Couples

  Kim Kardashian & Kanye West

• Celebrity Couples

  Andrew Garfield & Emma Stone

• Celebrity Couples

  Olivier Martinez & Halle Berry

• Celebrity Couples

  Jennifer Lopez & Casper Smart

• Celebrity Couples

  Ryan Gosling & Eva Mendes

• Celebrity Couples

  Kristin Wiig & Fabrizio Moretti

• Celebrity Couples

  Alec Baldwin & Hilaria Thomas

• Celebrity Couples

  Nick Loeb & Sofia Vergara

• Celebrity Couples

  Anne Hathaway & Adam Shulman

• Celebrity Couples

  Jessica Simpson & Eric Johnson

• Celebrity Couples

  George Clooney & Stacey Keibler

• Celebrity Couples

  Brad Pitt & Angelina Jolie

• Celebrity Couples

  Jennifer Aniston & Justin Theroux

• Celebrity Couples

  Jessica Biel & Justin Timberlake

• Celebrity Couples

  Ben Affleck & Jennifer Garner

• Celebrity Couples

  Joel Madden & Nicol Richie

• Celebrity Couples

  Jay-Z & Beyonce

• Celebrity Couples

  Prince William & Kate Middleton

• Celebrity Couples

  Mariah Carey & Nick Cannon

• Celebrity Couples

  LeAnn Rimes & Eddie Cibrian

• Celebrity Couples

  Vanessa Minnillo & Nick Lachey

• Celebrity Couples

  Carey Hart & Pink

• Celebrity Couples

  Blake Lively & Ryan Reynolds

• Celebrity Couples

  Blake Shelton & Miranda Lambert

• Celebrity Couples

  Liam Hemsworth & Miley Cyrus

• Celebrity Couples

  Neil Patrick Harris & David Burtka

• Celebrity Couples

  Portia de Rossi & Ellen DeGeneres

• Celebrity Couples

  Matthew Bellamy & Kate Hudson

• Celebrity Couples

  Scott Disick & Kourtney Kardashian

• Celebrity Couples

  Khloe Kardashian & Lamar Odom

• Celebrity Couples

  David & Victoria Beckham

• Celebrity Couples

  Tom Brady & Gisele Bundchen

• Celebrity Couples

  Miranda Kerr & Orlando Bloom

• Celebrity Couples

  Megan Fox & Brian Austin Green

• Celebrity Couples

  Stephen Moyer & Anna Paquin