"I am so grateful to have someone I love. I fall more and more in love with Kevin everyday," writes Spears, 23, in a Valentine's Day letter that she posted on her Web site Friday. She goes on to reveal that she has "a great surprise planned" for her hubby on Valentine's Day Monday.
Spears writes that the couple have been spending time apart while Federline, 26, promotes his own career, fueled by his recent cover shot in March's Details magazine. Federline recently told PEOPLE he's thinking of modeling as well as acting, producing music and designing his own fashion line.
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Tabloids have been frothing over rumors that Federline has been away from his wife and partying with his buddies – going out without his wedding ring and even getting lap-dances at strip clubs in Las Vegas. But Spears doesn't hint at any trouble in paradise.
"We've been away from each other for a week now and I think I'm losing my mind! It's the longest we've been a part from one another. He's working a lot right now and I'm so happy for him."
Spears, who recently purchased a $7 million, 9,000-sq.-ft. Malibu home, also speculates on moving closer to her mother once she and Federline settle down more.
"I think when Kevin and I start a family we might build our dream home right behind my mom's (house). It's true; home is where the heart is."
Spears wraps up her posting with some romantic wishes for her fans: "I hope you all have a wonderful Valentine's Day with the one you love. But if you're single, just round up a group of your friends and grab some low-fat Blue Bell ice cream. It's the best!!"