Sally Stiebel and Mark Ein at the Washington Kastles match Sunday. (Courtesy of the Washington Kastles)

Ein, 47, spent years as one of D.C.’s most eligible bachelors: A Chevy Chase native, he founded a successful investment firm and has donated serious bucks to local charities. A tennis buff, Ein met Billie Jean King at the U.S. Open in 2007 and founded the Kastles — with Venus and Serena Williams on the team — here a year later.

The never-married multimillionaire kept his personal life pretty low-key until he started dating Stiebel, 27, three years ago. She’s a 2007 University of Virginia graduate who works as a policy analyst at lobbying shop Mehlman Vogel Castagnetti. The two have been regulars at social events around town and, of course, all the Kastles’ matches this summer.

Ein proposed a few weeks ago on a beach in the Hamptons, although he tried to keep the news quiet by telling only family and a few close friends. But engagement rings have a way of getting noticed, and pretty soon friends were buzzing with the good news. When reached for comment Monday, Ein confirmed the engagement but declined to elaborate.

Stiebel and Ein at the BET Honors dinner in Washington in January. (Kris Connor/Getty Images)

Here’s an idea for a venue: The historic Beall-Washington House in Georgetown, better known as the former home of Washington Post publisher Katharine Graham. Ein bought the 19th-century mansion for $8 million in 2002 — but he still hasn’t moved in, though he’s co-hosted an elite pre-White House Correspondents’ brunch there the past couple of years. Works for weddings, too, we hear.
Read earlier: Mark Ein and Washington Kastles, Creating a buzz with winning and bold-faced names, 7/15/12

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