This poem is about a woman waiting for her lover in the tower, but she can see through the autumn water and not see anyone. Deep love cannot be transformed into melancholy and bitterness. The last sentence means: I am upset because I have been waiting for my lover for a long time, and I have been walking back and forth. I feel that although I haven't seen each other for only one day, it seems to be as long as three months. (That's right)