And nights bright days when dreams do show thee me.
If Shakespeare meant this as him only seeing this girl during his dreams, what does this imply about his daily life? Is this a crush, or something like being a stalker? If he is only seeing her as he walks by, and then dreams about her during the night, it seems like the things he feels for her are taboo. Maybe this poem is talking about how he feels for someone not his age and can only see her in his dreams.