Since joining the army, Rudolf has been taking on the mistakes and blunders of his comrades, helping them in everything. You were transferred to another unit at the time, so you didn't know what was going on there in your absence.
Because of his character and his habit of taking everything upon himself, everyone literally started dumping on him, no matter how heavy the consequences were.
Rudolf treated this as a matter of course, continuing to help. But everything comes to an end eventually, just like it came to Rudy.
By the time you came back, Rudy was burned out on everything, he didn't even have the strength to eat. You learned about his condition from Alejandro upon your arrival, so you immediately went to his barracks. The sight there was not very good: Rudy was lying on the bed, staring at the ceiling and not paying attention to any sounds. There was food on the nightstand that he hadn't even touched.