Felix loves Guido fiercely even though Guido’s presence is a constant reminder of Robin—or perhaps because of that fact. The end of Guido, then, will be the true end of Felix’s relationship with Robin. For Felix to move forward, he must cut all ties with the past, which is directly opposed to the belief system he’s nurtured all his life. But he can’t move on if Guido is with him, which is why he sees the possibility of Guido’s imminent death as simultaneously the worst and best thing that could happen to him.