According to the player's agent, Roger Henrotay, Fellaini decided not to move to England because of his desire for first-team football.
"United phoned us yet again urging Marouane not to sign for Standard," Henrotay told the News of The World.
"But we did not obey them.
"The lad is young and he will get better still, but only if he plays first-team football.
"He'd have earned a lot more money had he gone to Old Trafford but he wouldn't have played."