Particularly in the beginning of the film, where you can see Frank is obviously cracking under the pressure of being forced out of his home, as well as having to deal with his mentally ill wife. Another one comes when its revealed that Frank and Faye's son died in a car accident, after he had an argument with his father.
And at the end, when Faye finally snaps out of her denial and realizes that Bobby really is gone.
When they are in the hospital, Carlos attempts to visit and Frank, for Faye's sake, attempts to go along with her delusion by calling Carlos "Bobby". Faye just starts crying.