Mari took to Instagram on Tuesday and posted a slideshow of photos that she captioned, "IT'S A BOY!!!"
Mari teased her Instagram followers, who probably initially thought that Mari was pregnant with a child, by showing off little sonogram-like images of her new puppy. The slideshow also featured Mari and Kenny posing with the tiny brown and black furbaby.
Mari continued in her post's caption, "After a bunch of adoption applications and pre-naming every pup we applied for just on the 'chance' that we'd get to be their new pawrents, our lil family is now bigger by 4 legs and a wiggly little tail."
"Everyone, meet our new baby, Eleven! (IYKYK) -- we're not set on his name yet tho, so give us your suggestions too!" she added.
Mari proceeded to share how "Eleven loves following close behind feet, licking ears, and chewing cables."
"He also loves 'trying' to play with [our other dog] Monster, but Monster is just worried about trying to eat the extra serving of food that gets put out now," she concluded.
Kenny uploaded the same post on his own Instagram page, and celebratory and congratulatory messages poured in from Bachelor Nation, including Natasha Parker and Serena Pitt.
"My heart just stopped, I fully thought this was a pregnancy announcement!!" Serena commented.
And The Bachelorette alum Ivan Hall admitted, "Y'all got me. Definitely got me."
"We agreed that we're gonna do it in Puerto Rico, definitely," Mari said on the "Talking It Out With Bachelor Nation" podcast in April, although she and her fiance hadn't set a date yet.
Mari revealed that she and Kenny had "narrowed down" their wedding-venue options to four places and imagined having an outdoor wedding ceremony followed by an indoor reception with "tropical flowers" everywhere.
After Kenny popped the question in Paradise, Mari moved to Kenny's hometown of Chicago.
Kenny revealed in January 2022 that he and Mari were taking the next step in their relationship and moving in together.
"@Mari_Pepin and I have signed the lease on a new apartment here in Chicago," Kenny reportedly wrote on his Instagram Story at the time.
Mari then reposted the announcement and added, "I can't wait to keep annoying you, and scaring you, and love you every day boo!"
On Bachelor in Paradise's seventh season, Mari, a marketing manager at the time, connected with Kenny, a boyband manager, right off the bat despite their 15-year age difference, and it seemed like love at first sight.
But once things began getting serious, Mari pumped the brakes and suggested the couple should continue seeing each other while keeping their options open and pursuing other possible romances in Mexico.
Kenny, a little heartbroken over Mari's lack of commitment, therefore dated Demi Burnett, with whom he went to "The Boom Boom Room," and he also went on a date with Tia Booth in which they played naked volleyball with strangers.
Once Mari saw Kenny with other women, she realized how much she missed him and how she wanted him all to herself. Mari therefore apologized to Kenny and fought for him, and the pair became inseparable after their reconciliation.
"Obviously, I was very into Mari from the very beginning," Kenny explained to People in October 2021.
"So once I sort of knew she was in the same place I was is when I started thinking, like, we might end up engaged at the end of this."
Mari said she and Kenny are in similar stages in life and want the same things, which helped bring them closer together and solidify their bond.
"I feel like I'm kind of in a different life stage than most people my age. And so for me, I think someone who is in a similar stage [works best]," shared Mari, who revealed on Bachelor in Paradise she's not interested in partying and had always wanted to get married young.
"We do the same things and we've got the same habits, and it just works really well for us. So I think that's ultimately what I was looking for, and I found it."
Mari added of the significant age gap, "I think the only way that it's noticeable is when we talk about movies or music, because [we're] obviously [from] different generations."
On the Bachelor in Paradise finale, Kenny popped the question with an oval-shaped diamond ring and said, "Mari, I am so f-cking in love with you! And I can't see my life without you. You are an amazing woman and you've changed my whole outlook on life."
The pair couldn't wait to show off their love and be a couple in public.
Although Mari and Kenny had to hide their relationship from the public for several months while the show was airing, they didn't exactly follow the rules of their contract.
"We actually snuck [out] to [got to] a concert together. We saw Journey here in Chicago," Mari revealed to People.
"We weren't supposed to, but we didn't get caught. We both wore hats. I wore a pair of glasses, and it was really late at night, so it worked out."
In terms of having children, Mari said, "I think I just want to enjoy being married for a little bit first and then maybe in the next year to two years we'll start talking about that."