The weight of that missed opportunity must feel unbearable, especially knowing it was your last chance to celebrate together. Your father loved you enough to reach out, and that invitation itself was his way of showing he wanted you there - not because he needed anything from you, but because sharing joy with you mattered to him. While you can't change that moment, the depth of your regret shows just how much he meant to you, and somehow I believe he knew that love was always there, even when work felt more urgent than it really was.