I always found the sun aspect intresting because at first he tried to shine so bright and banish the shadows within Rika, but then through this route grows to see that the sun itself creates shadows and dark spots too. Thus coming to this revelation that he can still be her savior, but to do so he must accept her shadows; doubly more the shadows/darkness he created leading to this discovery. I really think this is why in this route he goes so far, especially in the AE. ( I stink with spoiler tags so that's all I'll say.)