Manchester United have failed to win for the third time in a row as they were defeated 2-1 by Bournemouth on Saturday.
Junior Stanislas broke the deadlock in the 2nd minute before Marouane Fellaini equalised in the 24th, but Joshua King scored the winner nine minutes into the second half.
“It is very disappointing because, in spite of the early goal, we came on very well in the match, scored an equaliser and we created more chances to score a second goal," Van Gaal said, manutd.com reports.
"We didn’t do that in the first half but we had the feeling in the players, the management and the staff that we could win this game. Then the set-play causes the second goal of Bournemouth and you cannot accept it as a player or a manager.
“But it has happened and then you know in, this kind of game, the club who scores the second goal is mostly the winner and they are also pressing the ball every time so it is also very difficult to come again in your game. That is how I have seen this game.”