The former Chelsea starlet joined the Blues from Genk in 2012, but found himself sidelined under manager Mourinho.
In 2014, Wolfsburg parted with £18million to sign the Belgian ace and, after being crowned German Footballer of the Year, he then moved to Manchester City for a club-record fee.
The decision by the Blues to sell their prodigious midfielder will surely irk fans who grown tired of watching Jorginho struggle to deal with the pace of the Premier League.
But the situation could have been avoided had the Portuguese sanctioned a loan deal to Borussia Dortmund instead of a permanent one.
“When I was at Chelsea, there was so much in the press about my relationship with José Mourinho,” the midfielder wrote in the Player’s Tribune. “But the truth is that I only ever spoke to him twice.
“The plan was always for me to go on loan for a bit. So I went to Werder Bremen in 2012, and that season went great. When I came back to Chelsea the next summer, a few German clubs wanted to sign me.
“Klopp wanted me to come to Borussia Dortmund, and they played the kind of football that I enjoy. So I thought maybe Chelsea would let me go.
“But then Mourinho texted me, “You are staying. I want you to be part of this team.”
“So I thought, O.K., great. I’m in his plans.
“When I arrived for preseason, the vibe was good. I started two of the first four games of the season, and I thought I played O.K. Not brilliant, but pretty good. After the fourth game, that was it.
“I was on the bench, and I never really got a chance again. I didn’t get an explanation. I was just out of favour for some reason.”
The move to the Bundesliga was the making of the Belgium international; he scored 13 goals in 51 games and equalled the record number of assists in a single season.
Manuel Pellegrini convinced the Manchester City board to part with £54million to sign the starlet and the rest, as they say, is history.
Mourinho was sacked midway through De Bruyne’s first season at the Etihad and the 27-year-old credits the former Manchester United boss for giving him ‘life-changing moment’.
He continued: “José called me into his office in December, and it was probably the second big life-changing moment for me. He had some papers in front of him, and he said, ‘One assist. Zero goals. Ten recoveries.’
“It took me a minute to understand what he was doing.
“Then he started reading the stats of the other attacking forwards — Willian, Oscar, Mata, Schürrle. And it’s like — five goals, 10 assists, whatever.
“José was just kind of waiting for me to say something, and finally I said, “But … some of these guys have played 15, 20 games. I’ve only played three. So it’s going to be different, no?”
“It was so strange. We had a bit of a conversation about me going back out on loan. And Mata was also out of favour at the time, so José said, ‘Well, you know, if Mata leaves, then you will be the fifth choice instead of sixth.’