Bobbi's maternal grandmother Cissy Houston had reportedly been upset about her granddaughter's relationship with Nick when the couple began dating in March 2012.
"What they're doing is incestuous," Cissy's friend had told TMZ at the time.
Bobbi has since argued Nick is not her actual stepbrother because he was never adopted into the family. Instead, Whitney raised Nick--- a non-blood relative -- like a son. Nick had allegedly lived in the Houston household starting at the age of 12.
"I'm tired of hearing people say, 'Eww your engaged to your brother' or if Whitney was still alive would we be together or would she approve of this?" Bobbi said last summer, according toPeople.
"Let me clear up something, we aren't even real brother and sister, nor is he my adoptive brother. My mom never adopted him. Mommy was the one who even said that she knew that we were going to start dating."
Whitney died at age 48 in February 2012, which quickly resulted in Bobbi having an emotional breakdown and getting hospitalized. Bobbi had previously co-starred in Bravo's Being Bobby Brown reality series with her father and Whitney in 2005.