All people want to be faithful and honest, but not everyone has the courage and fortitude to do this. I am sure that no one wants to betray of their own free will, there is always some kind of need, or temptation. And then the one who is weak in spirit will definitely prefer the curved path to the direct path. Therefore, I agree that devotion is a manifestation of fortitude.
For example, in N.V. Gogol’s novel “Taras Bulba,” Ostap remains a loyal defender of his fatherland, despite the hardships, danger, and temptation to flee the battlefield. We see that he had the same opportunities as his brother: being trained in a bursa, he could meet a girl, and indeed find himself a career that was not related to the war. But Ostap did not look for easy ways; he inherited a solid character from his father. Coping with difficulties, he remains an unwavering and loyal warrior. This is especially noticeable when the hero is captured. He is tortured in the square, and he is silent and suffers incredible pain. His fortitude allowed him to maintain dignity and honor even in the face of painful death.
Another example was described by A.S. Pushkin in the novel in verses "Eugene Onegin." The main character, despite a strong feeling long in life, did not change her husband. Her determination to follow moral canons is a fortitude that we see in the very young Tatiana. She conquers her inner fear and sends a letter to Onegin, where she very much compromises herself with a declaration of love. She could forever ruin her reputation, but she was not afraid of this. She took a risk to achieve clarity in relations with Eugene. The same firmness of conviction now pushed her away from him. She could not allow her kind and gentle husband to be deceived. Her choice is a strong-willed decision.
Thus, devotion is the destiny of strong and strong-willed people, while others are simply not able to make a moral decision when personal interest is at stake. That is why it is necessary to temper the strength of the spirit in order to be an honest and faithful person.