Rudy was devastated, not because he had met an accident where he would have definitely lost his life if he was a normal human, where Eric would have lost his life if Rudy hadn't saved him immediately after the accident.
Rather, he was devastated because he couldn't get the dragon girl's name in order to call her when he wanted to have a fun time.
'Wait a minute, even if I knew her name… how was she supposed to know when I called her name? It's not like she can hear me from the other side of the planet. And if she could, I don't really need to know her name to call her out.'
Rudy would have considered the possibility of the dragon girl fooling him and running away after making a promise to get out of the situation— if she hadn't left her heart with him.
"Well, I gained nothing and lost nothing." Rudy walked back to the crash site and looked at Eric.