THE whispers that socialite Tinsley Mortimer (above) and her high-school sweetheart, Topper Mortimer, are calling it quits are getting louder. Tinsley, who designs handbags when not navigating the cocktail circuit, and Topper, a hedge-funder, have been telling friends they’ve been split since December. “They’re separated, but they haven’t filed for divorce,” a source told Women’s Wear Daily. A source close to the couple tells Page Six: “Tinsley was getting fed up that their ‘don’t ask, don’t tell’ agreement was being violated by [Topper’s] promiscuous ways.” Neither party could be reached for comment.