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Despite Nick Gordon's denial to ABCNews.com that he and Whitney Houston's daughter Bobbi Kristina are dating, the pair were photographed at the end of last week walking hand-in-hand while Bobbi Kristina appeared to be wearing a large diamond on her ring finger.

The ring, a huge square-cut diamond, appeared to be the same one that Houston, herself, wore around the time of her death. Bobbi Kristina, 19, was seen wearing the ring on her left hand amid reports that she is engaged to the guy she once referred to as her brother.

Gordon did not immediately respond to ABCNews.com's request for comment. A spokesperson for the Houston family also did not respond immediately to a request for comment.

A source told Us Weekly that Bobbi Kristina and Gordon, 22, are indeed engaged and living together in Houston's Atlanta-area home.

According to TMZ, Gordon and Bobbi Kristina broke the news to friends at a backyard barbeque this past weekend, and then kissed in front of everyone. The website said they brushed off the suggestion that grief had brought them together.

The news is reportedly not sitting well with Bobbi Kristina's grandmother and Houston's mother, Cissy Houston.

According to Us, she is "really upset" and "worried" about the unconventional romance. TMZ reported that Cissy Houston told a close friend, "What they're doing is incestuous."

Although always close - Gordon often referred to Bobbi Kristina as his little sister - the relationship seems to have evolved in recent weeks.

Before closing his Twitter account, Gordon seemed to confirm their growing closeness, while neither confirming nor denying the reports that they were dating.

"Yeah, we got a little closer and what!!!" Gordon wrote last week, a few days after posting a photo of the two of them smiling.

Twitter/@Ndgordon

That was followed by "All the haters that don't know us or the real story can't unfollow me. I don't give a f**k." "I've proved my loyalty to her and the Houston family. I don't owe any of you anything. Ha, I don't even know y'all haters."

"Some ppl [people] have no lives so they gotta be in ours," he added.

Gordon also made it clear that the two are not related by blood.

"For the stupid ppl out there, she gave birth to 1 child. And she trusted me with EVERYTHING!!!!!!!!!!!!!"

He added, "She called me her "God Son." I swear some ppl in this world act like they don't have a brain …"

According to sources close to the family and a TMZ report, Houston invited Gordon to live with her more than 10 years ago after learning that his birth mother could no longer care for him.

Gordon was "like a son to her," her brother, Michael Houston, told ABCNews.com.