I'm rewatching season 5 and am looking for something where Buffy and Spike fall in love whether it's before or after going to bed together, possibly during or around Crush. Any recs for something good here?

Show Me by Behind Blue Eyes

During the episode Into the Woods, once Buffy discovered Riley's infidelity, she fled into the night. How would Buffy's and Spike's relationship have changed, if he followed her, instead of letting her go off on her own?

It's here on SR

Crash by Zyrya
http://www.sinister-attraction.net/stories/z/crash.htm
Crush goes a bit differently when Buffy gives Spike his crumb.

West of the Moon, East of the Sun is a season five rewrite that has one of the best Spuffy romances ever.