Zack and wife Michaela Clark had an explosive ending to their on-again, off-again relationship about a week after "Decision Day" wrapped, and Bao determined she wanted a divorce from Johnny on "Decision Day" although Johnny had requested to keep working on their relationship.
Once the show wrapped, Zack, Bao and Ryan Ignasiak apparently began hanging out all the time together, with frequent bar visits to play pool.
"I've gotten to know Bao over the last several months. I think she's an amazing person," Zack told the cameras. "I like how she's always herself. I love her giddiness, I really do."
While playing pool one day, Ryan left the gathering early and Bao suddenly noticed Zack's pool skills were faltering, which prompted Zack to admit he was "just nervous."
"I have a question to ask you," Zack began, explaining the source of his nerves. "So, we got to know each other pretty well over the last several months, and I've really grown to like you. And I would love to take you out on a date some time soon."
"Oh!" Bao replied.
"So if you would like to do that, we should go on a date -- a date to see if there's something more, if you agree," Zack said.
"Wow, that's pretty bold," Bao noted, before adding, "I'd be down for that, yeah!"
Bao, who was trying to process what just happened, told Zack that she had grown "very fond" of him, and Zack responded, "Likewise... [but] I was low-key nervous you were going to reject me."
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Bao said she was interested to see where things could go with Zack, who also didn't want to ruin their friendship.
Zack later FaceTimed with his brother Hunter and revealed how he had developed a crush on Bao after the show ended and that he and Bao have "way more in common" than he had with Michaela.
"I just like that she's open and willing to be herself in any situation," Zack shared. "I really like that. She's a really caring person and I think she's very good looking, and someone I just want to get to know more."
Zack wasn't sure if Michaela would care about him pursuing a romance with Bao, but he said he didn't "want any drama" and had moved on from his marriage to her.
"I think I waited for the perfect time... [and] Johnny definitely doesn't care," Zack noted. "He told the husbands a long time ago that if anyone wanted to talk to Bao, feel free. He doesn't care at all."
Hunter supported Zack's new relationship effort and thought it would be a nice little switch-up. Zack, however, was a bit nervous about trying to turn a comfortable friendship into a new romance.
"I think this is a risk worth taking," Zack told his brother.
Meanwhile, Bao gushed about how Zack made her feel comfortable to be herself and she liked how he has a close relationship with his siblings as the eldest.
Married at First Sight then documented Bao and Zack's first date at a romantic restaurant, where Bao wore a sexy red dress and Zack told his date that she looked "amazing," although he also admitted to liking Bao in her yoga pants.
"It's refreshing to feel like I'm being swept off my feet -- by my friend Zack," Bao gushed with a smile.
Zack told Bao at dinner that he was serious about finding a new relationship and he would prioritize her.
Zack and Bao subsequently attended a cast getaway together -- which did not include Gil Cuero and Michaela -- and they continued to get to know each other better.
Bao noted how she and Zack got along so well and there was promise for them as couple, and then Zack assured Bao that he was focused on her and going on a second and third date and so on.
"I'm only going out with you. I'm not going to be focusing on anyone else. So, it's going to be exclusive in that sense, but I'm not saying you have to do that," Zack told Bao.
"I want you to but that's not a requirement because it's early on, and I don't want to rush into things."
But then Bao confirmed that she did not want to "entertain any other options" either.
Bao anticipated going on more dates and hopefully coming out the other side with "something serious."
By the end of the getaway, Zack said he could envision a future with Bao and just wanted to be happy.
TheMarried at First Sight: Where are They Now? special also featured Rachel Gordillo agreeing to move back in with Jose San Miguel as well as Ryan getting back out into the dating pool.
Myrla Feria was shown buying herself a small dog, and Michaela had moved into a new townhouse for a fresh start.
Bao and Zack dating rumors surfaced all the way back in September based on fan sightings and photos that circulated online and on social media.
Bao and Zack were spotted filming with a camera crew at a restaurant at the time, which turned out to be the romantic-dinner scene that aired on the Where Are They Now? special.
Zack and Bao also later took photos at the same interactive art exhibit at The Museum of Fine Arts in Houston, and the @MAFSfan Instagram account received photos from eyewitnesses believing they had spotted Bao and Zack at the same club in early October.
Videos were even taken of Bao and Zack together at the club.
"Look Y'all, I am legally married (only because I'm contractual obligated to be) but very estranged," Michaela wrote in a series of posts on her Instagram Stories.
"I have not spoken directly to that man in months."
Bao also appeared to address Bao and Zack's relationship, without naming them directly.
"Whatever him and her have going on has absolutely nothing to do with me!" Michaela continued.
"I wish them the best. [I'm] happy for anyone who comes out of this process a happier, healthier version of themselves."
However, Michaela later suggested on Instagram that she views Bao dating Zack as a betrayal of "girl code" considering all the MAFS brides had become close friends during the season and Bao even supported Michaela through difficult times in her marriage to Zack.