James said after filming Seeing Red, he had to go to therapy. It messed with his emotions so badly. James is clear he believes Buffy is too go for Spike.

The more I think about the last days of Sunnydale, I can't blame Spike for not believing that Buffy didn't love him. They spent an amazing night together that he admitted scared him because he had never been close to anyone like that before. Then hours later he sees Buffy kissing Angel. She sends Angel away and gives the amulet to Spike. He feels she doesn't love him and he wants to make a difference by being the one to wear the amulet. He knows it's dangerous and doesn't want her to wear it. He feels like this is his moment to protect her and save lives. Nobel as can be, but sad since he doesn't believe her words of love.