To activate a Heart-to-Heart, the characters must have reached at least the required affinity and both be in the active party. Some Heart-to-Hearts can only be accessed at a certain time of day. It also appears to be required that the Heart-to-Heart of a lower affinity must have been activated already, though this may not always be the case. The scene can still be played out even if the characters have a greater affinity than required, and they are never locked out or missable. Some will not activate even with the required affinity until a certain point in the main story has been reached, indicated by a message box rather than the usual title box when attempting to activate.