"At first glance he looks naked lol," Demi captioned the racy images, which feature Demi in an orange bikini.
Demi's new love interest is acquisitions analyst Slater Davis, according toUs Weekly.
Demi debuted Slater as seemingly just a friend on February 13, when she posted a photo of them eating wine and cheese and doing face masks together.
But Demi confirmed they're dating -- or at least hooking up -- on Saturday when she posted a photo of them nearly kissing while out celebrating her 25th birthday.
"The present I never knew I needed," the Bachelor in Paradise alum wrote alongside the image, showing Demi leaning in for a kiss with her hand on the back of Slater's neck.
Demi wore a black lace top to the dinner and had her long blonde hair slicked back into a low ponytail, while Demi's new man, who sports platinum blonde hair, was wearing an orange and white shirt and had his nails painted black and white.
Demi first teased she was dating someone new last month.
"Me telling my parents I'm talking to a guy with a lot of tattoos: so what y'all think?" Demi tweeted in January. "My parents: he's so camouflaged we can barely see him."
Slater does, in fact, appear to have many tattoos.
"What has always been at the forefront of our relationship is love and care for one another. Our priority is doing what is best for us. With a heavy heart full of love for one another we have decided it is best for us to take a step back from our relationship," Demi wrote at the time on Instagram.
"We ultimately want what is best for us in the long run and for us right now, that means being apart and growing individually... We will forever be proud of the impact our love story has made and we hope it has helped others feel more accepted and confident within themselves."
Meanwhile, Kristian also apparently has a new love in her life, YouTube star Taylor Blake.
Kristian toldUs last week she's smitten with Taylor, whom she's known since they were both young teenagers.
"She's amazing and I'm so happy and thankful," Kristian gushed.
Kristian initially shared photos with Taylor around Valentine's Day in which the women were being very affectionate with each other.
The photos showed Kristian and Taylor touching noses, kissing and looking into each other's eyes.
Kristian publicly asked Taylor to be her valentine on social media, while Taylor wrote on her own page, "When I was 13 I wanted you to be my Valentine, but I was closeted and too scared to ask you -- So, I asked your cousin Luke to be my Valentine instead. Here we are at 27, and I finally made you mine. You were worth the wait, you little sh-t."
Fans began speculating their relationship was on the rocks in early October 2019, given they remained quiet on social media after posting photos of each other on September 19.
Demi told Us on October 9, however, she and Kristian were just really busy and forced to spend time apart due to their hectic schedules.
"Every relationship is different and it's like -- I mean in the most respectful way -- it's nobody's business how our relationship works. We both have so much going on right now," Demi said at the time.
"Just because we don't broadcast [our romance] doesn't mean that we're not together... I think it's important to kind of have our space."
Demi and Kristian were both living in the Los Angeles area at the time but never apparently moved in together.
When Demi began her stint on Bachelor in Paradise 6, she sparked a romance with Derek Peth, who quickly fell for the bubbly and outgoing Texas native hard.
Demi respected Derek and thought he was an amazing man, but she couldn't stop thinking about a girl back home, Kristian, whom she had been dating prior to her appearance on the summer spinoff.
Demi found herself so conflicted between her feelings for Derek and her lingering or unresolved feelings for Kristian that Bachelor in Paradise welcomed Kristian on the show so Demi could figure out where her heart was truly leaning.
Once Demi reunited with Kristian in Paradise, the women were able to further explore their connection. Demi knew immediately upon seeing Kristian in Mexico that they were meant to be, and so Demi let Derek down gently and continued to date the music video producer.
After enjoying a Fantasy Suite date together, Demi proposed marriage to Kristian on the beach and presented her with an engagement ring during Bachelor in Paradise's finale.
The reunion special subsequently featured Kristian proposing marriage to Demi and offering her a diamond sparkler as well.