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On-again, off-again couple Justin Timberlake and Jessica Biel have finally decided to tie the knot.

Us Weekly is reporting that Timberlake popped the question to Biel in the mountains of Jackson, Wyoming, in late December.

"Justin knows how much she loves snowboarding and the mountains, so it was the perfect place," the magazine quoted an insider.

Reps for Timberlake and Biel did not respond immediately to ABCNews.com's requests for comment.

Us Weekly says that after a three-month split in early 2011, Biel, 29, made it clear that she wanted to spend her life with Timberlake, 30.

"When they reunited, they had a conversation about taking the next step," a source told Us.

A friend of Timberlake said the Grammy-winning singer has "never been happier" with the "New Year's Eve" actress. "He knew it was the right time to propose," the friend was quoted saying.

In March last year, the couple broke up after four years, but their reps seemed to leave the door open.

"Addressing the media speculation regarding Jessica Biel and Justin Timberlake's relationship, we are confirming that they mutually have decided to part ways," their reps said in a joint statement. "The two remain friends and continue to hold the highest level of love and respect for each other."

Timberlake and Biel began dating in 2007, when their careers were on par: He was soaking up the success of his "FutureSex/LoveSounds" album and tour. She was cementing her status as Hollywood's It Girl, co-starring in the box office hit "I Now Pronounce You Chuck and Larry."

Then Timberlake invaded Hollywood and Biel picked up fewer parts. In 2010, his star eclipsed hers: While he showed off his acting chops in " The Social Network" and flexed his comedic muscles on "Saturday Night Live," she spent time on commendable, if not as high-profile, charity projects.