Does the reward for a person's patience in enduring the trial of excessive lust due to a psychological disorder vanish if they stumble and commit a minor sin in this regard?

Falling into sin once does not entirely negate the reward for the patience that preceded it; rather, the reward is lost for that instance only. Desire renews itself and demands renewed patience, and temptations are presented to the hearts "stick by stick" as mentioned in the Hadith. A person is rewarded according to their patience, and their reward diminishes to the extent they succumb to temptation. Therefore, seek Allah's help, strive against your lower self with patience and perseverance, and turn away from the whispers of Satan. We advise consulting specialized doctors regarding ways to alleviate desire.