Coutinho has become a phenomenal player this season and he has shown his talent to help Liverpool climb the Premier League Table. Rumours are that Coutinho is a transfer target for Barcelona and are looking for a replacement for Neymar. Although, Ronaldo Fenemeno has advised Coutinho against this move to Barcelona because the Catalan club has had issues with other Brazilian players such as Ronaldhino,Romario and Me. Last summer, Neymar left Barcelona for PSG and is now the star of the club. However, this is just speculation but there are high chances because Coutinho has said that he wants to leave Liverpool this season.
I can't see Liverpool letting him go in the current window (it would be a big mistake) but he'll definitely go in the summer.
He's a very important player. It's like Man City letting Kevin De Bruyne leave.