The word "bower" comes up in the diary on six occasions.On four of them (A26 , S3 ,O15, N9 ) it is preceded by the possessive "my," often followed by "little." on the other two occasions ( S24 , O26 ), it is in the phrase "our little bower," the "our" referring to Louisa and Thomas. It is "my" bower when she is visiting it by herself and "our" bower when she is visiting it with Thomas. It is a place where Louisa has spent "many happy moments" (A26, O15) and "many happy hours" (O26), and very likely it is the place identified in S8as her "favourite spot."
Evidently, the happy times in her bower are associated with Thomas and the summer. Her solitary visits there seem to be happy largely to the extent that they recall happy times, but depressing to the extent that she is not with Thomas and to the extent that the summer beauty of her bower has faded and the weather become cold and dull. As the fall progresses, her solitary visits seem to become more and more depressing to her, until by Nov. 9 it is "now bereft of all its beauty."