Many Buffy fan claim that Spike is Buffy's biggest love. This is totally wrong.Here I will explain why.
As we all know Riley is not Buffy's biggest love. He was just someone who helped Buffy ease her pain after Angel's goodbye. She used him only for sex.
Exactly the same happened with Spike. She never really loved him. He was a "sex machine". But with Angel it was different. Even if they did not have sex she stayed with him proving how much she loved him.
As te all know Buffy's "i Amore you" to Spike was not real. She told it because she knew he was going to die. But she told "i Amore you" to Angel not one but many times. And she meant it.
I could possibly find other things but I want to hear your opinion too.