Nicole Scherzinger and on-again boyfriend Lewis Hamilton are not engaged, despite reports claiming otherwise, a source tells Us Weekly Credit: Tim Whitby/Getty Images

Don't ring those wedding bells just yet. Nicole Scherzinger and her on-again, off-again boyfriend Lewis Hamilton are not engaged to be married, despite reports claiming otherwise, a source tells Us Weekly.

"He hasn't proposed," the source says. "They only just got back together at Christmas, so it's very much at a point of working things out still."

The former Pussycat Doll, 35, and her British Formula One racer beau, 29, have dated on and off for more than five years. They broke up and reconciled once in 2010, and then split again last summer. "It feels like this time it's for good," an insider told Us at the time.

A few months later, however, the two reunited. They've been working things out ever since. Last week, Hamilton (who races for Mercedes AMG Petronas) shared a photo of himself with Scherzinger at the Sistine Chapel in Vatican City, happy and clearly in love, with Hamilton even affectionately calling Scherzinger his "wifey."

"This was a great day...truly humbled by the Sistine Chapel, plus there with my wifey," he wrote alongside the pic. "#godisthegreatest #sistinechapel #blessed"