Mariah Carey and Bryan Tanaka are in "a proper relationship now" and acting like a couple in public as they continue to celebrate the holidays.

The Hero hitmaker is taking the words of her famous Christmas hit - All I Want for Christmas is You - to heart and, according to a source who spoke to Entertainment Tonight, getting serious with her singer/dancer boyfriend Bryan Tanaka, 33.

"(They're in) a proper relationship now. She's really into Bryan. He's with her 24/7," insisted the source, before adding that the couple isn't hiding its affection around Mariah's five-year-old twins, Moroccan and Monroe with ex-husband Nick Cannon. "Bryan is great with the kids and they like him a lot."

46-year-old Mariah is, however, keeping Bryan out of her Instagram posts from Aspen, Colorado where she has been celebrating the Christmas period. On Thursday (29Dec16) she shared an image of herself and the twins outside at night in the snow, and also thanked San Francisco-based travel and property rental company Airbnb for their very generous Christmas gift.

"We've had the most amazing holidays, dahlings!" she gushed, continuing, "Thank you @airbnb for the gift of this beautiful home & trip to Aspen." The home, featuring an oversized Christmas tree, gorgeous interiors and mountain views, as showcased by Carey on social media, is reportedly worth $22 million (GBP17.9 million).

Entertainment website mogul Perez Hilton was just one of many who wondered why her boyfriend was nowhere to be seen in the images and videos. Perez commented, "Where's Tanaka?"

Bryan, meanwhile, did share some of his own photos on Instagram, including one that appears to be taken inside the Aspen mansion on Christmas Day (25Dec16), in which he's wearing a giant evergreen wreath complete with its own Merry Christmas garland. He also posted a photo of himself in front of a scenic snowy backdrop on Wednesday (28Dec16), captioning it, "Enjoying these mountains... #Grateful".

Mariah also shared an Instagram video early on Friday (30Dec16) of she and the twins decorating a gingerbread house, with all three sporting festive pyjamas. Again, Bryan was nowhere in sight.

The We Belong Together singer first sparked rumours of a relationship with Bryan when the couple was photographed kissing on a beach in Hawaii in November (16), just a few weeks after she confirmed her split from her billionaire fiance James Packer.