Despite their closeness, what experiences does Mai feel unable to share with her American friend Bobbie in Lan Cao's Monkey Bridge? Why?

Despite their closeness, Mai feels unable to share with Bobbie her continuing sense of doubt and despondency about her future in America.

In the second chapter, Mai and Bobbie are on their way to Canada to place a phone call to Vietnam; the purpose of the phone call is to locate Mai's grandfather in the Southeast Asian country. Canada didn't participate in military offensives during the Vietnam War and as such, was considered non-belligerent in its war stance. Because of Canada's (at least on the surface) neutrality, Bobbie feels confident that telephone connections to Vietnam would enable them to easily locate Mai's grandfather.

For her part, Mai is less optimistic about their ability to succeed in their efforts. She realizes that she has inherited too much of her mother's cautionary nature to feel buoyant about the outcome of their mission. Part of the reason she feels that she can't share her experiences with Bobbie is because she treasures Bobbie's "sweet, uncorrupted innocence." Bobbie's innocence stems from never having witnessed the horrific scenes of war that Mai had been exposed to in Vietnam.

Even during their travels, Mai can see helmeted soldiers, tanks, and barbed wire in her mind's eye. Ugly scenes of carnage often cloud her vision, and she often finds the most ordinary of tasks overwhelming and sometimes, surrealistically macabre, as when she imagines (during a trip to the mall) Bobbie's index finger taking on the dimensions of a soldier's brutally maimed trigger-finger. Mai's private torment is further reinforced by the privations she was forced to endure before she emigrated to the United States. For her part, Bobbie has been raised in relative security and has no frame of reference to understand what Mai has gone through.

So, Mai feels unable to share her war experiences and her fears regarding the future with Bobbie. Part of the reason stems from the fact that she feels self-conscious about her fears; another reason is that she cherishes Bobbie's innocence, something she wishes that she still had. Perhaps yet another reason is that Mai fears her friend may be unable to fully relate to her anxieties about the future and her grief about the past. Indeed, from Bobbie's point of view, her friend is safe in Canada and should have nothing to worry about; she doesn't realize that people like Mai often suffer from survivor's guilt and other emotional stresses even after they have been rescued.