Lost His Soul

All I remember is that at some point in the fic (I think towards the end?) Buffy finds out Spike lost his soul after NFA. I remember Spike was really moody in the story too. I think it was a longer fic? Maybe?

The only ones I can think of where Spike chooses to lose his soul are...

Prophecy and Warmth by TheBear
Post NFA Buffy is with human Angel and Spike is abroad with a slayer called Carlotta. Giles fetches Spike/Carlotta for their help with a side effect of the slayer activation spell which is threatening the lives of slayers. I think Spike gave up his soul so Angel could get the shanshu reward.

A Not So Gorgeous Mistake by Kari Mouke
But that is post S7 where Angel is rewarded his humanity for fighting the first and Willow removes Angel and Buffy's memories to give them the suburban life together but Buffy keeps remembering Spike.

Sounds like it could be Prophecy and Warmth - which is amazing and you should read it even if it's not the one you're looking for. I've got several in which Spike has lost his soul - some short, one or two longer ones. Usually he has made a bigger deal of it than Buffy has. I think Anaross also has one in which Spike came back without his soul... it could be the wonderful My Life Closed Twice. I think it is, and it is toward the end when he tells Buffy he doesn't have his soul anymore. (If memory serves - which sometimes it doesn't...)

It was Prophecy and Warmth! Thanks guys!