The result means the Londoners have now failed to win in four successive home matches in all competitions, with the last victory coming against Newcastle on December 10.
"It is always the same story," Jol said. "You go one up and you need another goal but cannot score another goal and then you are vulnerable.
"It is easier said than done but when you are 1-0 up you still have to dominate the game.
"We had a little problem to contain them and they had players in the pockets but we are a big team at the back.
"But we needed a second goal and we did not score a second goal. It was the same against Southampton when we needed second goal and didn't score and they scored an equaliser.
"We have a problem in our balance but we have quality and that will pull us through but we have to score two goals.
"Last year, if we scored one goal it was decisive. This year most of the time, it wasn't decisive."