Eddie betraying Rodolfo is an act done out of love, hate, desperation and possessiveness. I disagree to a larger extent that what Eddie had done was just to save Catherine from a marriage without future. Instead, what Eddie did was more for himself than for Catherine.
             Since the start of episode 1, Eddie had portrayed himself as a very protective person over Catherine, as seen when he voiced his concern about Catherine's new job "I don't like the neighbourhood over there". The relationship between uncle and niece is very close as Catherine looks up to him quite a lot. "Almost in tears because he disapproves". However, this relationship began to decline with the arrival of Beatrice's cousins, Rodolfo and Marco. Trouble began brewing as Catherine's attention began to waver and heard towards a certain handsome blond man, Rodolfo, as seen when Catherine praised Rodolfo's singing so much. "He's terrific! It's terrific, Rodolfo".
             No matter how good a man can be, it is fairly obvious to me that the main reason that drove Eddie to betray Rodolfo was not to save Catherine from a marriage without future, but that Rodolfo had been annoying him since the first day they met, and he wanted to get rid of that annoying source in the easiest way possible by letting other people, the immigration officers, do it.
             Rodolfo ticked Eddie off so much because not only was he young and handsome, and a bit effeminate, Rodolfo was also cool and ambitious. "I will buy a motorcycle". Also, in episode 2, we can see that Catherine began to dress more maturely by wearing high heels just for Rodolfo. Also, the subtle innuendos exchanged on their first day of meeting each other as shown in the sugar scene, "yes! I like sugar very much!" ,only makes Eddie more jealous as he can only realize he is old and he cannot be compared to a young , cool, ambitious and handsome young ...