Why doesn't the White Knight continue on with Alice? "I don't know," Alice said doubtfully. "I don't want to be anybody's prisoner. I want to be a Queen." "So you will, when you've crossed the next brook," said the White Knight. "I'll see you safe to the end of the wood - and then I must go back, you know. That's the end of my move
-Through the Looking-Glass, Lewis Carroll

O He cannot go with her.

O He chooses not to go.

O He cannot cross the brook.

OAlice does not want him to.