Jessica Simpson‘s secret B-day surprise for BF Tony Romo that may lead to the altar!

Jessica surprised lover doll Dallas QB Tony Romo with a $100,000 custom speedboat for his birthday.

Tony, who turned 29 on April 21, was stunned by the pricey gift, says a friend of the couple. "Jessica knows that Tony has always wanted a boat."

But this isn’t just any boat, the pal points out. The custom 25-foot Malibu Wakesetter has a 450 horsepower motor.

 "Tony loves speed, and with all of the horsepower in his new boat, he can go as fast as anyone on the lake," said the pal.

Jessica, 28, had the boat delivered to the house the couple shares in the Dallas area, where Tony’s posse gathered for an impromptu party.

"Jessica is hoping that her birthday gift to Tony will lead to marriage, and by this time next year that she’ll be walking down the aisle with him," added the pal.