Mr. Grape's death left an indelible mark on his widow. Mama, who Gilbert claims was once "the prettiest girl in these parts," has become morbidly obese. Mrs. Grape won't leave the house and although she clearly loves her children, she has been debilitated since her husband's death. Her compulsive eating habits reflect her desire to stuff her pain deep inside, to smother her anger and fear with food. In fact, Mrs. Grape's overeating is mirrored in the way she treats Arnie: twice in the movie she bear hugs him, squeezing as if she could smother him. When Arnie is taken into police custody, she leaves the house for the first time in eight years. Her willingness to leave the house proves her love for her son and also enables her to experience an emotional catharsis, during which she screams in anger, "I want my son!"

Becky is the catalyst of the movie. Her free-spirited lifestyle and personality help heal Gilbert's sullenness and help Arnie to overcome his fear of water. Moreover, Becky's impact on Gilbert extends to his relationship with his mother. Whereas Gilbert once held little kids up to his living room window so that they could gawk at Mama, at the end of the film Gilbert proudly introduces Becky to Mama. Becky is enthralled by sunsets and her outlook on life is open-minded and whimsical. Her and her mother's vagabond traveling lifestyle reflects their attitude toward life.

Betty Carver's affair with Gilbert covers up her deep dissatisfaction...

She ignores her children, who scream and act belligerently. Betty, who is probably in her early 40s, becomes highly dependent on Gilbert for emotional sustenance. When it appears Gilbert may be losing interest in the affair, Betty throws an emotional tantrum out of desperation. She tries to remain in control of her relationship with Gilbert by asking for a grocery "delivery" whenever she wants attention. She also displays a need for control by her desperate pleading with Gilbert to not leave her. However, Betty is desperate for the type of love and intimacy that Gilbert is incapable of giving her.
Gilbert's relationship with his mother and his siblings reveals a set of psychological coping mechanisms that he cultivated in response to the death of his father. For example, on the surface he is kind to his mother and never talks back to her. He treats her as he treats Arnie: like they are fragile creatures. However, behind her back, Gilbert talks badly about his mother, calling her a "beached whale." Gilbert and Aimee, who is the oldest child in the family, get along well and in fact rarely talk or interact. With his younger sister Gilbert is far more antagonistic. She is sarcastic and belligerent, and accuses Gilbert of acting too fatherly. Her belligerent attitude irks Gilbert and causes him to lose his temper a few times, but in general, Gilbert displays enormous love and respect for all his family members.