The moment played out on the latest episode of 'Flipping 101.'
Heather Rae Young is supporting her fiancé. The 34-year-old Selling Sunset star took to Instagram on Thursday to share a clip from the latest episode of Flipping 101, which shows her sitting next to Tarek El Moussa as he learns he has celiac disease.
In the clip, Young holds El Moussa's hand as a doctor explains his diagnosis, which he had "no idea" about.
"You have a gluten allergy. When you ingest gluten, basically your intestinal lining starts to fight it. If you stay gluten free, one, you'll feel better, two, the risk of cancer is much, much lower," the doctor tells the 40-year-old HGTV star, who previously battled cancer.
"So my favorite foods or live better and healthier and longer?" he responds, before turning to Young and asking, "Gluten is in everything! What do I eat?"
In a confessional, El Moussa admits, "I wasn't really expecting that news, and it's just going to be a really big change for me."
In the caption of her post, Young called the episode "a really important one."
"Celiac disease was something Tarek had never even heard of (classic him) and it’s something that a lot of you might not know about," Young wrote. "We knew something was making him extra inflamed and I was extra worried because as a lot of you might know, Tarek has had two types of cancers in the past and I wanted to be one step ahead of anything because obviously I want him to live forever and be as healthy as possible."
With El Moussa's past health issues in mind, Young said her fiancé got "a bunch of blood tests," which his "amazing doctor" was ultimately able to use to diagnosis him with celiac.
In the comments section of her post, Young thanked fans for their support and gave an update on how El Moussa was adjusting to his new diet.
"We have been doing a lot of gluten-free, plant-based meals at our home," she wrote. "Everyone is adjusting and we are getting used to the changes and Tarek is loving a lot of the gluten-free food."
"I just cannot wait to marry this man! It's gonna be a beautiful wedding and it is coming up," Young told ET's Matt Cohen earlier this month. "We're getting close."
After they say "I do," El Moussa and Young are thinking about starting a family. El Moussa is already dad to Taylor, 11, and Brayden, 6, whom he shares with his ex-wife, Christina Haack.
"I never thought I would have babies, and I never saw that in my future. I always wanted to get married but... it just seemed like I couldn't be a mom. I just didn't know," Young told ET's Lauren Zima. "And so, I'm like, 'Well, babe, what's one more?' You know, our life's already crazy and, you know, maybe."
"She just started hinting at this like a few weeks ago, but at the end of the day, listen, she's my wife," he said. "There's one thing I know about children. I would never regret having a child because I love my babies so much. So if we have more kids, we have more kids."