i never explain

Oz.

He's patient. He sees Willow and asks thinks about it, thrn her out, even with the awkwardness. He adores her for who she is. He gets her little gifts because he thought of her. He asks if she's ok with things and says he's not ready, when Willow suggests they sleep together. He's very sweet and gentle about his no too.

When Willow cheats with Xander he tells her the truth. She says sorry so she can feel better. He's not vindictive or cruel but he sets his boudries for dealing with it. He tells her what he felt. Even though he has a wolf/monster inside of him, he controls the anger and instincts, and steps away to understand it. Oz missed her and says he's willing to give things another shot.

He acts like the most adult and emotionally secure character in the group.

Even when he's with Veruca. Yes., it's a mistake but he accepts and takes responsibility. Never spiteful. He leaves because he needs to. Even his short return to find Willow and Tara. He knows what's best and she cares for Tara, so even heart broken, Oz wants Willow to be happy.

In the end, Oz was the "best" guy on Buffy the Vampire Slayer. I'll just always be a little disappointed he never got the full character and story arch he deserved.

HOWEVER, Buffy doesn't necessarily know for sure if she loves him completely and with the same voracity that Spike wants her to. We're way too early and they've barely had a conversation about a relationship between them. Buffy hasn't had time to even consider what these new feelings for him are so I definitely think there's a hint of insincerity from rushing into that (most likely) romantic confession.

You could argue she fell for Angel super quickly in contrast but 16 year old Buffy just didn't have the same guards around her heart as she does by the time Season 7 comes along.