I once read a great book that started off with the main character- who was a (mathematically-specialized) hyper-space pilot/(and I wanna say assassin)- that was attending a supernova viewing party. Later he falls in love with a God who becomes a planet and manifests herself from a pool on said planet.
This is definitely a book by David Zindell, most likely Neverness. The woman who becomes a godlike cybernetic entity is called the "Solid State Entity" (encompassing not just a planet, but an entire solar system) and she's one of several such AI deities in the book, and in that larger fictional continuity, which is also the setting for his trilogy, A Requiem For Homo Sapiens (The Broken God, The Wild, War in Heaven).
One of the most distinctive aspects of the continuity is the existence of a guild of hyperspace pilots who navigate through the universe by discovering new and unique mathematical theorems.
Neverness is one of my favorite books, but I never read the trilogy, so the only reason I hesitate at all about the identification is because I don't remember the supernova viewing party. The mathematical pilots and the Solid State Entity are both in Neverness, but they are likely to also appear in the trilogy as well.