Singer Britney Spears will tie the knot for the third time after her longtime boyfriend Jason Trawick reportedly proposed to her. Spears, who has two sons, Sean Preston, five, and Jayden James, four, with second husband Kevin Federline, got secretly engaged to Trawick when the 39-year-old talent manager asked the question by writing her a romantic poem. After filling the ground floor of the couple\'s Los Angeles mansion with roses and candles, Trawick reportedly presented the 29-year-old with a flower-shaped diamond ring, reports the sun newspaper. \"She\'s on cloud nine,\" femalefirst.co.uk quoted a source as saying. The Toxic hitmaker is also looking forward to planning her first child with Trawick, but only wanted to do it once she had tied the knot again. \"Britney is desperate to settle down again and have more children. But she is very traditional and didn\'t want to start a family with Jason until they tied the knot,\" the source added.