"Yeah. [I have done] nothing, is a discussion between the player and the board. I'm not involved in contracts in deals, and I respect both, I respect the player because he has the right, has the right to decide his future, and I respect the board because the decisions and the discussions are under control so I just wait wishing they will have an understanding but it's out of my control?"
Mourinho has been a vocal supporter of the Belgium international since taking over at Old Trafford in 2016, per Goal:
Despite debate among fans and pundits alike as to whether he lacks the required quality to play for an elite side, Fellaini has proved a useful asset for United since he joined from Everton in 2013.
What the Belgian lacks in finesse, he makes up for in sheer physicality, and Mourinho has effectively made use of that by deploying him as something of a battering ram in the final third, where his height and strength make him a real handful for defenders to deal with.
ESPN's Alex Shaw recognised as much, but he believes United would be better off letting him leave if it is proving difficult:
Fellaini has proved his worth at Old Trafford, but his usefulness is relatively limited and he could be upgraded upon.
Mourinho is evidently eager to keep him, though. The Special One is probably downplaying the influence he has over his players' futures, but even if that is not the case, the club will be aware of his preference.
As such, unless Fellaini's demands are excessive, you would expect United to make a concerted effort to tie him down.