A 24-year-old Manhattanite’s steamy love affair with a Miami nightlife mogul two decades older than her was lost at sea when they were involved in a boating accident that erased her memory of their relationship.

Brooke Biederman — whose parents are famed urban planner Dan Biederman and fine-arts lawyer Susan Biederman — was secretly dating former party boy Michael Capponi, 44, for more than a year when they got into the love-destroying crash last March.

“She is my soulmate. And she called me hers,” a heartbroken Capponi told The Daily Mail. “Now, I made it my mission in life to let Brooke know the truth about our relationship and love.”

But despite penning dozens of love letters to her and even starting a public Facebook page where he shares the notes and old photos, he hasn’t talked to her since the fateful night of March 20, 2015.

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That night, they jetted out on his 25-foot Chris-Craft motorboat to watch the sunrise when Capponi, who was steering the water vessel, unexpectedly blacked out and crashed into a Coast Guard retaining wall.

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