"This is something they've both wanted for a long time," the source told Us. "It's a way to cement their family. They're both extremely happy and can't wait to become man and wife." The couple plans to celebrate their engagement tonight at Planet Hollywood in Las Vegas.
Trawick was Spears' manager from 2008 until earlier this year, when he stepped down from the position to focus on their romantic relationship and his plans to open an arts and entertainment division for Famos LLC, a company whose partners include Mick Jagger and Dave Stewart.
Trawick's professional relationship with Spears began shortly after her father, Jamie Spears, seized power over her finances and career decisions via legal conservatorship. Spears' father has given Trawick permission to marry his daughter, but he will be forced to sign a prenuptial agreement.
Earlier this year Sam Lutfi, Trawick's predecessor as Spears' manager, filed a motion in Los Angeles Superior Court to push a judge to order a psychiatric evaluation of the pop star to prove that she is capable of testifying in court, which could potentially lead to Spears' father losing control over her career and estate.
Earlier this year, Trawick and Spears shared the screen in the video for her song "Criminal," which you can watch below.