Married at First Sight viewers were updated on the Season 13 cast members' lives during Lifetime's Where Are They Now? special on November 24, which showed Bao and Zack going on a date and ultimately deciding to embark on a serious, exclusive relationship about four months after "Decision Day."
(Decision Day had featured Zack asking for a divorce from his MAFS match, Michaela Clark, and Bao choosing to also divorce her MAFS husband Johnny Lam).
But Elena Guevara, a 21-year-old cosmetology school student who relocated to Houston from Ohio this fall, insists that -- unbeknownst to either woman -- Zack was also dating Elena and having a sexual relationship with her for over a month until Elena realized he was seeing both of them at the same time and reached out to Bao.
Earlier this week, Elena posted alleged "receipts" of some of her text messages with Zack on Reddit to try to prove Zack had spent a month-long period from late October to late November cheating on Bao with her.
And then on Wednesday night, Elena conducted a YouTube interview on India and Michelle's channel to explain why she had decided to expose Zack in such a public way.
During the YouTube interview, Elena said a few weeks after moving to Houston, TX, a friend who watches Married at First Sight suggested she reach out to Zack because he's "cute" and "definitely" was likely currently single given how rocky his marriage to Michaela had appeared on the MAFS episodes that had already aired on Lifetime by that time.
Elena -- who says she wasn't a Married at First Sight viewer herself -- therefore decided to go "out on a limb" and give a shot at dating an "older man."
So, after sending him a follow request on Instagram (since MAFS Season 13 was still airing on Lifetime, Zack's Instagram was private) she also sent him a direct message on October 25 saying, "Hey," and Zack allegedly quickly replied with his phone number.
Zack allegedly told Elena that he wasn't allowed to accept new Instagram followers so they would have to use regular text messaging instead.
However, rumors that Zack and Bao were involved in a post-show romance had also already begun circulating online in September, when the pair had been spotted enjoying a romantic dinner together followed by subsequent museum and club dates.
But as someone who wasn't a Married at First Sightfan, Elena said she hadn't heard the rumors that Zack was dating Bao -- and that even after she began seeing him, the only MAFS footage she watched were clips that Zack would occasionally show when they'd be hanging out at his apartment during dates.
"I had no idea about [spoilers Bao and Zack were together], and he had told me that we weren't able to go on dates in public because we'd be photographed together and posted on a blog," Elena claimed in the interview.
"He told me that if he was photographed with another woman, then the show would sue him because everyone had to be under the impression that he and Michaela were still married because people couldn't know about the divorce and he couldn't file for divorce yet until after 'Decision Day.'"
According to Elena, she remained in the dark about Zack's relationship with Bao until last weekend, when Bao posted a gallery of Instagram photos that appeared to show Zack and Bao had spent Thanksgiving with Bao's family and one of her friends noticed the photos and brought them to Elena's attention.
"My friend was like, 'Isn't that Zack?'" she explained during the interview.
Elena said she then tried to confront Zack about his relationship with Bao on Sunday, November 28 and he denied it.
"I tried to have an adult conversation with him about everything. I even tried to confront him about Bao on Sunday. I asked him, 'Why did you not tell me that you were dating someone?' He said, 'I'm not,'" Elena claimed.
Elena said she then decided to take matters into her own hands and sent Bao a direct message on Instagram that same day.
However, at some point Elena also apparently posted a public comment Bao's Instagram posting that said, "I wonder if she knows that he's been sleeping around with other women in Houston" in an alleged attempt to let Bao know what was going on, but instead it only seemed to result in an influx of backlash from Bao and Zack fans.
Bao then allegedly replied to Elena's direct message on Monday, November 29 and things "blew up" from there.
According to Elena, Bao began by asking her for Zack's phone number and address as evidence she really knew Zack. And then Elena sent "all the [additional] proof she asked for," resulting in Bao asking if Elena could call her so they could talk.
"We had like a 20 minute [Instagram audio] call and I told her everything, and she was honestly in disbelief and clearly very hurt," Elena claimed.
Elena said once Zack was caught, he "played the pity card" and allegedly tried to get both Elena and Bao to feel sorry for him.
Elena, however, told India and Michelle that Zack bounced back very quickly and asked her not to post any of their messages on social media.
Neither Bao or Zack have publicly confirmed Elena's breakup claims yet, however Bao has stopped following Zack on Instagram.
During the month they were dating, Elena said Zack had had told her he wasn't talking to or dating another girl. To make matters worse, Zack allegedly told Elena that he hadn't even dated anyone after deciding to divorce Michaela.
"I assumed I was the only one he was talking to. He told me that he wanted to be serious with me, and he told me that I was perfect and I was his dream girl and I had everything he's ever looked for in a girl," Elena said.
"And so, he was the only guy I was with, and so I assumed he was doing the same."
Elena expressed how she had been patient, supportive and understanding in her relationship with Zack while the show was airing because she "really thought we had something."
But even after speaking with Bao and ending things with Zack, Elena apparently still remained upset about the backlash she was facing on Instagram for her prior public comment, so she decided to join Reddit's popular Married at First Sight subreddit to "save her image" by sharing a collection of screenshots showing her text messages with Zack, as well as their initial Instagram connection.
"People were coming at me basically saying that I was some crazy fan girl, and I was like, 'Listen, I am going to save my image because I did not do anything wrong,'" Elena explained about the series of Reddit postings she made earlier this week.
The screenshots of Elena's alleged text messages with Zack on Reddit were intimate and at times sexually explicit, and a couple of the uploads have since been deleted.
In one of the screenshots, Elena alleged that Zack occasionally spent time with Bao and herself back-to-back on the same days.
Zack's alleged "I'm not [dating anyone]" text-message exchange was also one of Elena's screenshots.
"I really just wanted everyone to see his honest, true colors. This is the kind of person he is. He manipulates women," Elena noted, adding that she believes Zack used Michaela.
"This is a repetitive thing for him. He is constantly using women for sex, and it comes to my attention that I was not the only other woman."
Elena claimed she has been contacted by other women since she went public and now also knows "there were other women involved" with Zack besides herself while he dating Bao.
"He told me that his type is Hispanic women... The other women have come forward to me but asked to remain anonymous. They are also Hispanic," Elena said on the YouTube channel.
"He always told me about Michaela. He said, 'I was never attracted to Michaela, from the second we got married' -- and this and that. He said, 'She's not my type.'"
Elena also admitted she's sensitive to a man being unfaithful because she's been hurt in the past and she didn't want to be slut-shamed or treated like a mistress when that's not who she is at all.
"I said, 'I'm going to do this for the sake of women in the future, down the road,'" Elena explained.
"You need to know that this is the kind of person [Zack] is, and don't allow yourself to be manipulated or deceived by the facade that he puts on. He's very good... at putting on a mask."
Elena admitted she "couldn't stand to see him glorified anymore."
"He is the one who is wrong. I did nothing wrong... and Bao doesn't deserve any hate," Elena said. "The only person to blame is Zack."
Elena now believes Zack must have triggered and been at fault, at least to some degree, for Michaela's outbursts and knee-jerk reactions on Married at First Sight's thirteenth season, for which Michaela has been heavily criticized.
Elena also shared another surprising detail in the video -- that Zack's new best friend from Married at First Sight, Ryan Ignasiak, allegedly threatened her to "lawyer up" because he's going to sue her.
"I didn't do anything wrong. I said, 'What are you going to sue me for, telling the truth?'" Elena quipped.
Elena concluded that she has "undeniable evidence and receipts to back up every claim" she has made and she only posted a few of them on Reddit to spare herself some of the more personal details.
"I think [Zack]'s silence is speaking volumes for him," Elena said, wrapping up the interview.