A source told the mag, "They are so excited. And very, very happy."
Olivia reacted to all the well wishes from fans on Sunday. She tweeted, "Thanks for all the sweet congratulatory love, friends! And may I compliment your savvy use of that nifty engagement ring emoticon."
She had previously denied the engagement rumors. In December the 28-year-old wrote on the social networking site, "No I'm not engaged but I AM at the Stones show and holy s**t Ronnie Wood you got style, boy. It's just a fact. Trying to score a shoe pic."
The celebrity couple has yet to set a wedding date.