Love is a decision-making process. One does not love without making the critical decision at the opportune time. In the case of "Tristan und Isolde", the love potion represents this decision both lovers have to make. It might even represent the marriage that was never meant to happen.
However, Wagner's music is so transcendental that such a fuss about the potion can only distract rather than helping us to indulge in this immense Gesamtwerk and in this superb and complex music, in particular.