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"Finally reunited!!!" she wrote in the caption. "Kissing and loving on his baby boy. @therealtarekelmoussa I missed you so much."
Tarek, 40, went away to Cabo with his entire extended family including son Brayden, 6, and daughter Taylor, 10 — the two kids he shares with ex-wife Christina Hall. Heather, who is expecting her first child with Tarek, had to miss the getaway on doctor's orders.
A rep for Heather told PEOPLE that the decision for Heather to skip the trip came out of an abundance of caution, to avoid risks such as Zika virus and food poisoning. Heather shared with PEOPLE that her doctor told her, "It's not worth getting sick. Chances that you can avoid, you should. Unavoidable exposures are different."
Heather Rae El Moussa Instagram
Earlier this week, Heather admitted to having some "separation anxiety" in an Instagram post on Wednesday.
"Missing my best friend while he's away in Cabo with the kids and our families so I'm going through photos that I love of us 🤍 " the reality star wrote in the caption, alongside a gallery of photos from their pregnancy shoot.
She continued, "This is the longest we've been apart since we've been together so I'm maybeee getting a little separation anxiety 😆 so help distract me! What are your favorite books/tv shows at the moment??"
RELATED GALLERY: Heather Rae El Moussa Bump Photos
"Family trips to Cabo are always a good idea 😎," he wrote in the post's caption. "Staying in a villa with my entire fam and our kids and having a blast ❤️ Experiences like these are nothing without your family or close friends to share them with 🙏 So if you need the El Moussa fam, we'll be here:)"
"Just missing @heatherraeyoung like crazy but doctors orders come first!!" he concluded the caption, mentioning his wife.
Responded Heather: "Miss my family ❤️❤️❤️❤️ and love you so much baby."
Another photo from the vacation was posted by Tarek to Instagram on Wednesday, showing him standing with his kids on the beach. "The three musketeers take Cabo! 😎 It's not the same without @heatherraeyoung but we're holding down the fort over here doing a whole lot of jet skiing, swimming, family dinners, and just having the best time," the Flip or Flop star wrote. "Enjoying every moment before it's back to work for me and back to school for the kids! ❤️"
"All this warms my heart I miss my love so so much," Heather commented on the photo. "Can't wait to kiss you tomorrow my love."
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Heather and Tarek were in the middle of in vitro fertilization treatments and had even scheduled a date to transfer an embryo next fall when they found out they were expecting, they told PEOPLE exclusively last month.
The pair, who are in the middle of filming their new HGTV docu-series The Flipping El Moussas, are expecting a baby boy early next year.