That's one story that doesn't hold up very well. Rudolph had at least two other mistresses at the time besides Maria Vetsera, was on morphine and had been diagnosed with VD. He had attempted to talk one other mistress into suicide with him previously. Only the 17 "Mary" would agree, and left farewell letters to her mother and sisters behind at Mayerling. Her tomb was ransacked by Russians in 1945 and the battered condition of her skull later discovered, was held up as proof that she'd been beaten to death instead of shot. But others have said that one entrace and exit bullet hole could still be seen on the damaged skull. Rudolph was a depressed cad who didn't want to die alone.
Yes...which would seem to make it even more unlikely that he would want to give up everything for her, "including the throne and the opportunity to take action on political changes in which he had long been interested" (Bogle).
In any case, this thread is about Emperor Karl, who we can agree was a vastly superior character.