Memphis apparently proposed marriage to Christmas on the beach during the couple's romantic getaway to Little Palm Island Resort & Spa on Wednesday, June 23.
"She said yes!! I love this woman unconditionally and I can't wait to spend the rest of my life with her. #final2forever," Memphis captioned a slideshow of photos.
Christmas posted similar photos of the big moment on her own Instagram account and wrote, "We knew we would love each other forever. I'm just so excited to officially say YES!!! #final2forever."
Christmas also admitted in her engagement post she is "still in shock" to have a diamond ring on her finger.
"I had no idea this was coming but I'm so glad it did. @memphisgarrett you are my home, my forever," she wrote.
Christmas called her ring "perfect" and her vacation at Little Palm Island a "stunning and enchanted experience."
And finally, Christmas added, "THANK YOU to @bigbrothercbs for throwing our crazy butts in a house for 3 months! You knew we would fall in LOVE!!!!!! #myhome."
Memphis and Christmas were both in relationships with other people when they competed on Big Brother: All-Stars, the show's 22nd season that wrapped in October 2020, so neither person acted on the romantic feelings they may have had for each other during the game.
"He's so great at making me feel like I'm the most special person in the world every day, and this day was the most of all," Christmas shared on Friday.
"I had no idea it was going to happen then. I know, a beautiful island, sunset at a beautiful resort... who wouldn't have guessed? I didn't! That's because that's the kind of thing he does regularly to show me how special he believes I am."
Memphis shared with the website how he had created a custom engagement ring for Christmas and "reviewed so many diamonds" before selecting "the perfect one."
Memphis told Us Weekly in December 2020 that he knew around Week 6 there "was something about her" he wouldn't be able to ignore, but the pair did not begin dating until after the show.
Christmas previously said she and Memphis bonded over being single parents onBig Brother.
"We have such a unique and fascinating story of how we fell in love and came together," Christmas told E! News.
"It's wild to know Memphis and I fell in love with each other before we even shared a kiss. He's my best friend, twin flame and brings out the best of me everyday."
She added, "We accept each other as we are and love one another for who we are at our core. He's my home."
But Memphis hinted in his interview with E! News that he noticed Christmas long before their stint onBig Brother together.
"Before I even met Christmas, I felt a cosmic attraction to her," Memphis revealed. "Once we spent 24/7 together for three months, I knew she was the one that I would spend the rest of my life with. I knew I found my twin flame."
Christmas and Memphis finished Big Brother: All-Stars in fourth and fifth place, respectively, and both of them ultimately voted for Cody Calafiore to win the game over runner-up Enzo Palumbo.
Big Brother's 23rd season is set to premiere with a live 90-minute episode on Wednesday, July 7 at 8PM ET. The broadcast will air on tape delay in the West Coast.