For those out of the loop: Apparently, Icardi's wife, Wanda Nara, and his contract renewal with Inter are the main issue in this whole thing. I don't know the whole story but it seems like Wanda likes to cause troubles on social media by calling out the manager every now and then for his decisions in some games, and obviously, the club doesn't like that (she's a big public figure in Italy). Plus, Inter doesn't like the way she's been handling Icardi's contract renewal (she's her manager).
Now Inter has had enough of Nara's behaviour, and also Icardi's attitude regarding the whole thing (seems like he doesn't care what her wife/manager does), and they've decided to remove his captaincy. Icardi's response? He decided not to play with Inter tomorrow in the Europa League. I don't know if he'll leave the club, only time will tell, but this whole thing is a mess. Will he go to Real Madrid in the summer? Real Madrid's president already said that they don't need a new striker because, according to him, they have the best '9' in the world.