Romance and friendship often produces a pile of hurting all around, but I don't think in terms of culpability. Buffy and Spike danced a very long dance together that left Spike with the strong impression that she'd want him to move on when she was ready for him to not be there any more. Spike is acting on that. To assign culpability is to say that Spike had some obligation to try to maintain the relationship and I don't see that he did, any more than I think Buffy had any obligation in season 7 to signal to him that she didn't want him to move on when the battle was over. She gave what she could. Spike's now giving what he can. Between the two of them they've never managed to give enough to actually get them together. That happens sometimes, and it's nobody's fault if there's just not a huge magnet working to make things come together.

Also, I don't think I'd want to call Spike's main motive fear. I think he honestly thinks she'd want to move on, and it would be perfectly reasonable to interpret Andrew's portrait of the situation as consistent with a Buffy who is relieved that Spike's not tracking her down and making her retract the ILY. He could honestly think he's doing exactly what Buffy wants him to do.

My last word is just a reminder that Spike thinks Buffy has had some post-Chosen agency in the question of whether they should communicate. He's wrong about that. But it's important to remember when thinking about his POV. He's not just deciding for her in TGIQ. He thinks she's decided something on her own.