Mary's experiences in Young Sheldon season 5 provide context to Sheldon's behavior towards his friends on The Big Bang Theory. After Mary was fired and betrayed by her church community, Sheldon believed that everyone would ultimately betray him too. This led him to act out at times just to see how much he could push his Pasadena-based friends until they left. However, over time, Sheldon learned to trust his friends and mellowed down, though he sometimes still acted selfishly. His friends stayed patient with him because they believed his behavior wasn't usually intentional. If Mary continues to be betrayed by her community, it will reinforce the idea that Sheldon's behavior towards his friends was motivated by seeing his mother's suffering.