Normal sudoku rules apply. The digits are dating. They have formed three couples and one throuple (a couple but with three people). The make-ups of these relationships are to be discovered. A heart between two cells indicates that the digits in those cells are in a relationship. ALL hearts are given. Clues outside the grid give the sum of the digits between the outermost members of the throuple in that row/column. eg If 123 are the digits in the throuple and the last row is 46 1(935)2 87 then the clue would be 17 (9+3+5).