Kristine said it was "hurtful" to see Keith holding onto these "risque" photos and they made her feel "a little insecure."
"I've seen enough. The fact he hasn't deleted these photos yet makes me feel like he still has feelings for his ex, and that worries me," Kristine said in the episode.
During a Tuesday appearance on Married at First Sight: Unfiltered hosted by Jamie Otis, Kristine revealed what happened after she discovered the pictures of Keith's ex.
"I wasn't very happy, I can tell you that much," Kristine expressed with a laugh.
"No, I mean, I was furious to be honest with you. I saw them and was just like -- you can see whatever on social media, you know? Go through some clicks and you can see some butt, you some boobs, you know? So I expected some screenshots or something in his phone."
"But I wasn't expecting them to be all of his ex-girlfriend," she elaborated. "They had broken up over a year ago and you have hundreds of pictures in your phone. Like, what is this?!"
Jamie then asked Kristine if she believes it's possible Keith could have just forgotten those photos were in his phone.
"No, I didn't think he forgot the photos were there," Kristine confirmed. "I had never seen anything that told me he might be going back to [look at] those photos, but he could have been! You never really know what happens."
Kristine, however, came to the conclusion she and Keith simply treated their past relationships differently.
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"Once they're done, I'm like, 'Alright, see you later!' you know? I'm like, 'I'm getting rid of everything you have because I'm starting fresh!'" Kristine said.
As a result of her own approach to breakups, Kristine thought her husband would be on the same page given they both chose to move on from the past and enter a marriage.
"Moving into a marriage, you've got to get rid of those things," Kristine noted.
Regardless, Kristine confirmed Keith has "definitely deleted" the photos since their heated conversation.
"I helped out with a few -- just a few," Kristine joked. "There was just a little level of insecurity that comes with knowing [Keith] had a relationship with this person and he had feelings for her and then he still had these photos. Like, get rid of them!"
Kristine acknowledged Keith having "nude photos" made the situation much worse.
"I don't think I would find anything good. I didn't do a lot during the phone-swap exercise and I could've actually dug a lot deeper," Kate noted with a laugh.
"But I feel like I probably would have found some bad things. I just looked at his contacts and found somebody named 'Dirty Skank' or something."
Luke explained to Kate off-camera the woman with that ugly title in his phone was a former co-worker whom his ex-girlfriend apparently didn't like. When the ex found out the co-worker was "hitting on" Luke all the time, Luke's ex named her "Dirty Nasty Skank" in his phone.
Kristine also said she has not checked Keith's phone since the exercise.
"From that day, I was like, 'I'm going to trust he [deleted them], because if I don't then it's just going to build.' You know? It would just continue to be negative, and it could all be in my head because I don't know what's going on," Kristine told Jamie.
"So I just kind of had to trust that they were gone."
Dr. Pepper hoped thousands of women were listening to what Kristine had just said because it was "a smart choice."
"It is a choice to trust and it is a choice to go in the direction of belief because that is what will support your marriage the most," Dr. Pepper reasoned. "I think that's great that you made that decision. I think it was the right decision."