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Wedding bells are in the air for Jillian Michaels, and it's been that way for several months, although few people knew about it.

Jillian Michaels, the former "Biggest Loser" trainer, has been secretly engaged to her longtime partner, Heidi Rhoades.

Jillian proposed to Heidi on the finale of the couple's E! reality show, "Just Jillian." The finale was filmed about four months ago, but the couple kept their happy news limited to just a core group of trustworthy family members and friends.

The finale and the proposal aired on March 8.

On the show, marriage had been a tense subject. Jillian was often against it; Heidi desperately wanted to marry her love.

Heidi won the the war.

For the proposal, Jillian and many of her friends and family tricked Heidi in to thinking they were all going to watch a movie in a theater. Then, though, a video began playing showing images showcasing the couple's life together.

Jillian's words flashed across the screen in segments that eventually read, "In a world where it's tough to connect, one woman found that someone special and came to discover that where there's love, there's hope, happiness and endless possibilities."

"We were a great couple but better as a family and eventually a zoo," it continued with Heidi seemingly not having an idea yet of what was happening.

"I have been thinking a lot and while so much of life is unknown there's one thing I know for sure, I want to be with you, for better for worse, in sickness and in health for the rest of my days," the words read, "so I only have one question for you…"

Then photos showed the couple's loved one holding up signs that read "Will You Marry Me."

As people in the theater clapped and the video ended, Jillian than got down on one knee.

"I know I'm an a------ all the time, but if you will continue to put up with me, I would like you to marry me," she said to Heidi.

The couple began dating in 2009 and are parents to daughter Lukensia, 5, and son Phoenix, 3. Jillian adopted their baby girl from Haiti the same week Rhoades gave birth to Phoenix.

"Heidi is the perfect person for me. The only place where there's like a solace … a safe haven is with my family," Jillian said in a voiceover following the proposal. "And Heidi is the nucleus of that family. She's the glue that really holds everything together, and I think without that, I would be lost."