According to a source, the romance is new because the Flip or Flop star has only been dating Nate for "about a month," E! News reported.
Christina, 33, was spotted at the Anaheim Ducks hockey game on Wednesday night with one of Nate's buddies and reportedly cheered the hockey player on from the stands when his team took the win over the Edmonton Oilers.
"She was in a really good mood," an insider shared with the website, which reported Christina previously attended several other games this season.
Dating rumors first sparked when Nate posted an Instagram photo of Christina and himself (see below) at the Lady Ducks fashion show, a charity event the women's hockey team put together for the Children's Hospital of Orange County, CA.
Christina and Nate had also allegedly been spotted chatting it up during the Ducks in Tux charity event in January 2017.
While the HGTV star and Nate, 32, appear to be dating, Christina's representative is denying that's the case.
They are "just friends," the representative said in a statement several hours after telling E! News that Christina is "single and not dating anyone" when people initially speculated she was on a date with the man whom she was sitting next to at the hockey game.
Christina and her estranged husband Tarek El Moussa -- who share daughter Taylor, 6, and son Brayden, 19 months -- separated in Spring 2016 but didn't publicly announce their split until December of last year.
Tarek, who co-stars on Flip or Flop with Christina, filed for divorce in early January. Like Christina, Nate is also divorced and shares a son with his ex-wife.
Christina was previously linked to her family's former contractor Gary Anderson, but the couple split in February. At the time, Christina's rep told Us Weekly that being in a relationship was "the last thing" on Christina's mind and she was taking time to "focus on her children and herself" post-divorce.
Christina echoed those sentiments in recent interviews about a week ago, telling the press she has no interest in dating right now and romance is totally off her radar.
As for Tarek, he was briefly involved with their children's former nanny, Alyssa Logan; however, he insisted in early March it will be a long time before he enters a relationship again.
Christina and Tarek may not get along perfectly on the set of Flip or Flop, but the blonde beauty assured Entertainment Tonight earlier this week her dynamic with him is great right now thanks to "letting go of past resentment, living in the future and remembering that kids are the priority."