Ball, who made less than $9.50 an hour as a retail worker, paid close to $860 to attend a meet-and-greet in England on Feb. 12, where she met the multimillionaire.
According to the Daily Mail, Ball and Mayweather were seen leaving the event together and driving away in a Rolls Royce.
Ball later sat courtside with Mayweather at an L.A. Lakers game, alongside power couple Beyonce and Jay-Z.
Since then, she's reportedly flown on Mayweather's private jet to visit cities like Amsterdam, Las Vegas, New York and Los Angeles during an extended trip to the U.S.
But the 19-year-old's mother said the relationship is completely platonic.
“She's only 19, and she's got a boyfriend," Ball's mother, Mandy Ball said. "Floyd asked her if she wanted a (vacation) in America and why would she refuse?”
Mandy Ball also asserted her daughter has a 19-year-old boyfriend back in Britain named Andre Brown. Brown posted on Facebook saying his girlfriend has his "love and support," the Daily Mail reported.
Ramarni Ball is said to regularly attend events where fans can pay to meet celebrities.
The aspiring entertainer has posted photos with other stars, like Trey Songz and Rita Ora.
Ramarni Ball's sister, Relissa Ricketts, is also believed to be accompanying Mayweather and her sister on the extended trip.