Yeah, but why tease? To what point? I mean sure, once or twice, but over and over and over again?

He's not been subtle about the fact that Spike isn't in the story, he points at the fact every chance he gets. Then makes a huge point of only showing Spike with Angel. We see Angel by himself, but we never see Spike without Angel - when he is shown. And when he's directly mentioned? It's in connection with Angel - "having met Angel, I'm now totally team Spike" or
"everyone who loves me dies, or goes to hell, or burns up.."
- the only time we get the word spike stated without Angel is in Angel/Twilight's presence - "there's a spike in magic"?
And it is in conjunction with magic.

That's a bit obvious. The writer has a reason for doing that.