Matteo is very jealous of Luna and Simón's relationship. In the first season, it can be easily justified by the fact that both he and Simón have feelings for Luna. In the second season, however, it has been established that Luna has no romantic feelings for Simón, he is apparently over his own feelings for her, and yet Matteo still gets upset every time he sees them together. It suddenly makes sense when one remembers that Luna and Simón are Childhood Friends; Matteo's family has always travelled a lot, moving countries almost every year, so he has never had the chance to form any long-lasting friendships until settling down in Buenos Aires for a longer time.
