[Marco]

I haven’t played SE 3 but I think that if you make the retreat option cost 2 or more strategic movement points, the retreating ships can't go far away. Once exhausted the strategic movement points left, they will be blocked for the rest of the turn.
I think that the problem is the direction of the retreat in the strategic map if the retreating ships not belong to the moving player, in this case there is not the possibility of a “backward move” in the strategic map and this can trigger others tactical battles. A possible solution is to allow retreat for defending ships only in strategic location without enemy ships and, if possible, in a direction opposite to the direction from where the attacking ships came from in the strategic map.
Marco.