The fitness expert, 43, was reportedly shocked when Riley suddenly called off the engagement over the weekend.
Anderson’s reps declined to comment to PEOPLE.
Anderson announced that Riley, her longtime boyfriend, had proposed on Feb. 5.
“Going into the week and the rest of my life with my true loves kiss!” Anderson wrote on Instagram. “It’s only been three days and I’m already the happiest bride to be on the planet!”
Anderson’s rep confirmed to PEOPLE that Riley had popped the question during a trip to Aspen for her annual Vitality Week summit.
Anderson, trainer to Gwyneth Paltrow, Lena Dunham and more, has previously been married twice, and has a 14-year-old son, Sam, from her first marriage, and a 4-year-old daughter, Penelope, from her second.
“Tracy, Nick and Tracy’s two children are thrilled, and enjoying this special time together,” her rep told PEOPLE of their engagement.