The look they give each other is enough to establish Spike’s feelings for her. I just rewatched the scene yesterday before posting and it’s fairly obvious there are feelings there. But to add the “I love you” from her would be to muddy what that love is, and there’s no way to get an answer when Sarah is not a part of the story.I agree with all that is said above, and yet it's a continuing minor plot point that Spike has feelings for Buffy and wants to go to her in Italy. I actually can't remember how it is clarified on Angel that Spike is in love with Buffy (probably because I already knew it from Buffy), but showing her saying, "I love you," would have been a quick way to establish that.
Only fair, given how the Spuffy Fan Showrunners ran BtVS 😅Typical Bangel fan showrunners