In a heartfelt video posted on his Viddy account, Trawick praised the singer for her work on The X Factor USA.
"Princess, we just completed our first weekend in Austin on X Factor," he says in the video. "Just wanted to say I'm very proud of you and I love you so much. Congratulations."
After watching the video, Spears tweeted her love back at her fiancé, writing: "Awww love you too Xoxo (sic)."
Rumours emerged earlier this week that Spears had walked off the set of The X Factor USA, but she quickly denied the reports.
Fellow judge Simon Cowell rose to the singer's defence, insisting that there had been no walk-offs on the show.
Spears signed a $15 million (£9.3m) deal to serve as a judge on The X Factor USA.