Before he left London, Van Gaal told some staff he did not know if he would see them again, although the 64-year-old said later he still “hoped” to be in charge for the final year of his three-year contract.
Van Gaal said “it’s over” when a reporter approached him as he left the hotel on Sunday – but he is said to have been referring to his side’s season rather than his own job.
Other members of Van Gaal’s Old Trafford staff are believed to be unhappy at the lack of communication from the club’s hierarchy.
United’s executive vice-chairman Ed Woodward, as well as Joel and Avie Glazer, part of the American family who own the Premier League club, were at Wembley on Saturday – but they are not thought to have spoken to Van Gaal at a function following the 2-1 win over Crystal Palace.
As the reports about Van Gaal’s impending departure grew in volume, the function is said to have been a sombre affair.
Neither Van Gaal nor Woodward addressed staff collectively in the wake of the club’s first triumph since Sir Alex Ferguson’s retirement in 2013.
In the past, Ferguson or former chief executive David Gill would have expressed their gratitude for the hard work involved in winning a major prize.
The silence must end soon as, with United failing to qualify for next season’s Champions League under Van Gaal, the Old Trafford hierarchy is thought to have decided a change is required.
BBC Sport revealed on Saturday that United are set to appoint Mourinho as the former Barcelona, Bayern Munich and Netherlands manager’s replacement.
Mourinho is preparing to hold direct talks with senior United officials on Tuesday. Assuming final details can be agreed, an announcement and formal unveiling could happen quickly.
His agent Jorge Mendes is currently on a business trip in Shanghai but will leave to return to Europe on Monday.
The Portuguese, 53, was sacked by Chelsea in December, seven months after the Stamford Bridge club won the Premier League title.
Mourinho, who won three league titles in two spells at Chelsea, has been out of work since.
He was at heavyweight boxer David Haye’s win in London on Saturday evening but repeatedly declined to comment on whether he was about to succeed Van Gaal.
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