German news outlet 20 Minuten reported Monday the "Summer Sadness" singer confirmed the breakup when asked if rumors that she was engaged with O'Neill were true.
"We are currently not together," said the 28-year-old star. "He is a wonderful person. But there are some things with which he has to deal."
"I will not explain it in detail," she continued. "This was hard on our relationship. I no longer felt free. We'll see how it goes."
E! News points out that Del Rey's quotes are not verbatim as they were translated from English to German and then back from German to English.
Del Rey, who has been very active on Twitter while promoting her latest album Ultraviolence, has not yet addressed the rumors on social media. Most recently, the singer tweeted at Frances Bean Cobain to address her claims that the singer glamorized death.
A rep for Del Rey had no comment when asked about the reports.