You really don’t know love until you’ve heard the notion dissected and choked down, swallowed whole and half-digested, then regurgitated over and over again in Tom Stoppard’s “The Real Thing.” That’s not to say, of course, that it isn’t a pleasant, if liberally roving, meditation on all things hearts and flowers. Just don’t expect Stoppard to wax poetic on Cupid’s bow or the semantics of a warm embrace — as his title indicates, it’s not exactly puppy love he’s interested in shoving under the microscope.