Georginio Wijnaldum was one of the standout performers in the group stage of the European Championship.
Only Cristiano Ronaldo scored more goals than the Netherlands midfielder, who found the net three times in three games.
The system was controversial among Dutch supporters and players, who favoured a more traditional 4-3-3 system, but De Boer's decision was vindicated by the Netherlands' displays in the group phase of Euro 2020.
Liverpool have strict rules over what they will offer to players over the age of 30, and they refused to budge despite Wijnaldum's ongoing importance to the team.
“I met this wonderful player for the first time – we played, obviously, against him – in my living room at home. I had to see him and talk to him," Klopp said.
“From the first moment it clicked between us, he’s a very friendly, very smart, very open person and that never changed, it just improved since then.
“Yes, it’s very emotional for me, because I lose a friend and we’ll miss him. That’s how it is.
“But it’s normal in football that these kinds of things happen. Not nice, but normal. I’m really sure he will find a great place.”
