I don’t remember where exactly (pinterest, I guess?), but I once saw a comment saying that Buffy didn’t love Spike at the end of the show and only said “I love you” to comfort him.
And that feels so strange to me, because it completely goes against her character arc.
Buffy is afraid of opening her heart to people. Back in s4, she even talks to her mom about how it would be easier not to open up at all—just to avoid the pain.
Open your heart to someone, and he bails on you. Maybe it's easier to just not let anyone in. ("Fear Itself")
Because in the end, everyone leaves Buffy. To the people around her, she’s just a phase in their lives, not someone who stays part of it—and that hurts her deeply. So deeply that she ends up building armor around her heart and stops throwing words around carelessly.
But then something terrible happens—Joyce dies. And after going through the loss of the person dearest to her, Buffy realizes she never said those three little words to her mom.
And I loved her more than anything, and... I don't know if she knew. ("Intervention")
For her, the words “I love you” are the hardest thing to say. She forgot how to express what she really feels—and now it’s too late.
Maybe being the perfect slayer means being too hard to love at all. I already feel like I can hardly say the words. [...] Giles... I love you. Love, love, love, love, love.. ("Intervention")
And then comes the ending of s7. Buffy knows Spike is about to disappear—just like her mom did. But this time, she has the chance to speak—and she takes it.
To me, this isn’t just a moment of realizing her feelings for Spike and reconnecting with her inner fire.
It’s one of the moments she was able to open her heart again and honestly say how she feels out loud. The moment her love was stronger than the fear of what might happen if she says about it directly.
The fact that Spike didn’t believe her—that’s his reaction, shaped by his own experience throughout the show. But the fact is—now he knows how she feels. Because Buffy didn’t hint at it—she said it outright.
That’s why I don’t think it was just about comforting a dying man. Because “I love you” means way too much to Buffy for her to say it lightly.