1. Spike made a deal with someone to give up his soulmate/true love to change something. I don't remember what. I do remember he thought he was giving up a life with Buffy, but it turned out it was Xander who dies.
2. Xander is Spike's Vampire's True mate but Angel's SOULmate. Xander has to choose between them. (he picks Spike) I think the Scoobies found out about Spander and they ran from SunnyD.