It might be more helpful to break down the poem into groups of stanzas, as often the emotion in one is carried on into the next few. Therefore, if we look at the first three, we could say that the emotion we could attach to these stanzas is one of sadness. Note the references to the fading of nature as winter draws on, the sedge withering and the silence of the birds. This withering is of course mirrored by the knight's own withering:
I see a lily on thy brow
With anguish moist and fever dew,
And on thy cheeks a fading rose
Fast withereth too.
If we then examine stanzas 4 to 8, we can see the emotion is one of passion and love as the knight remembers meeting the eponymous lady of the poem's title and the time they had together. The final stanzas see a shift towards despair and fear as the knight experiences his dream and then finally wakes up to the reality of how the woman has enchanted him and left him "Alone and palely loitering."