If you're going to place any credence on what the writers knew when they had Spike wear the amulet instead of Angel, the writers also knew, though we didn't (well, actually we did, because by the time that "Chosen" aired, the news was already out that Spike would be moving over to Angel's show the next season) that the whole reason that Angel was given the amulet in the first place was so that HE, not Spike, Faith, or Buffy, would wear the amulet into the hellmouth, thus becoming bound to W&H the way that Spike was when he first came back.
To me, the main reason that Buffy sent Angel back to LA had no more to do with actual romantic feelings than it did with that lame "second front" crap (Really, now, just how effective a fighting force would Angel be able to gather and prepare to fight off an army of ubervamps and Bringers in the few days that he would have had to do it?) The truth of the matter, the tactical reason to send Angel away was quite simple. You don't put two pit bulldogs together and expect them not to spend as much time fighting each other as the enemy, and that's exactly what Angel and Spike were at that time. Bringing Angel into the fight at that time would have been just too disruptive to an already volatile situation. The Scoobies/Potentials mutiny was barely settled, and any more disruptions at that point would have done far more harm than good. (Is there anyone here who has the slightest doubt that Giles would go into apoplexy, and Xander would pitch a running duck fit if Buffy brought ANOTHER vampire ex-boyfriend into the fight?)
So, the Spuffies believe that Buffy sent Angel away so that she could play snuggle puppy with Spike for a few more uninterrupted nights, and the Bangels believe she gave the amulet to Spike to wear because she could bear losing him more easily than seeing Angel die again. Almost certainly, the more logical explanation was that at that moment, she was in her General Buffy persona, and her decision was made purely for tactical reasons. The snuggle puppy thing with Spike was just a bonus.