It could also mean that Sakura represents something to Asuke in the fanfic. For example, she might be a symbol of hope or change. His dreams about her could be his subconscious mind's way of processing his own need for transformation or a better future, and he associates Sakura with those things.
Perhaps the dreams are a plot device in the fanfic to create a certain kind of tension or relationship dynamic. If Asuke is having these dreams, it might lead to some awkward or interesting interactions between him and Sakura when he's awake. It could also be a way for the author to explore Asuke's character more deeply, by showing what goes on in his mind when he's asleep.
One possible interpretation could be that Asuke has some repressed feelings for Sakura. In fanfic, dreams often symbolize hidden desires or emotions. Maybe in the story's context, Asuke has been around Sakura a lot and unconsciously developed an attraction to her, which is expressed through these dreams.