De Jong is playing very well right now. I think the reason why he didn't leave Barca was because of his love. This could be an expression of his love for Barcelona. Also, if he goes to Manchester United at this point, it will take him a long time to adapt and there are doubts whether he can play in the first XI. These are my personal opinions.
I agree that De Jong has love for the club and that will be the fundamental reason why he decided not to leave in the summer, he wants to play for the club but wants his wages owed to be paid, in my opinion it was a wise opinion to stay back at the club where he already build a fan base and good relationship with the players and coaching staff already. THere he feels at home and will play better.
De Jong didn't go to Manchester United because of any love for Barcelona. There is nothing like love, at that De Jong did was for himself and his interest. He felt that he needs to play champions league football to be more recognised in football and another thing is Barcelona technically held him back with buying off stories that Manchester United will pay. He is a good player and he is having