i keep thinking about the final spuffy scene in the show and how any convo just focusing on whether buffy really means it when she tells spike she loves him or if he believes her misses the point tbh.

she loves him. and i think spike believes her - but that's not the point anymore. he's gonna die because it's what a good man would do.

here he has thing thing he always wanted: buffy's love. the thing he went to hell and back for, got his soul back for. and him saying, "no, you don't." is him saying, i'm not doing this so you'll love me. i'm doing it because it's what needs to be done.

that's why spike's (temporary) death is actually really vital to the completion of his redemption arc. loving buffy made him become someone who sacrifices everything to save the world. it's how his love for her comes full circle from being "selfish" in nature to completely selfless.

but besides all of that, he wants her to be free. he wants to make it easier for her to leave him to die there. and buffy understands that. that is a moment of complete love and connection and understanding between them.