The pair have been dating since 2018, with Jillian telling PEOPLE that their engagement meant she could "officially call her mine".
"DeShanna is 'all the things' — beautiful, smart, funny, creative, quirky, passionate ... I could run down the list of adjectives. Those characteristics obviously attract you to someone. But it's the quality of their character that makes you think 'Thank God for this person laying next to me' every night when you fall asleep," the trainer said.
"It's easy to stay together when everything is going great, but when real life sets in and things get messy, challenging, scary, and even downright ugly — that's when the truth reveals itself. And this woman has revealed herself to be strong beyond measure, wise beyond her years, and loving beyond my wildest dreams. I am so grateful to officially call her mine."
Jillian Michaels appeared on the first three seasons of Australian Biggest Loser as a trainer, as well as on the American version of the franchise.
Last year, the 47-year-old spoke about her decision to leave the show after a decade, explaining she struggled to come to terms with the way she was being portrayed.
“In the beginning of the show it was tough love. You saw the tough, and you saw the love,” she told PEOPLE. “You saw none of the relationships, none of the bonds that I build with my clients."
Jillian went on to say that the portrayal created a "warped negative perception" of her and even began to impact her personal life with her former fiancée Heidi Rhoades and their children Phoenix and Lukensia.
But the former reality star is still training off screens, with DeShanna right by her side.
Just last month, the pair marked their three-year anniversary with loved up Instagram tributes.
“We are all asleep until we fall in love” Happy Anniversary @deshannamarie ❤️ I adore you," Jillian wrote.
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