Jack Grealish struck Everton's winner in injury-time at Selhurst Park.
Glasner said after the 2-1 defeat: “It's disappointing and very painful because it's completely unnecessary. It's our fault, it's our responsibility. We played so well over 60 or 70 minutes with enough chances to decide the game.
“(Tiredness) would be a cheap excuse. We're never looking for excuses. We could have decided it in the first 60 minutes, and we had then fresh legs on the pitch.
“That's the missing link to be a top team in the Premier League, to take the chances to decide the game when you can decide it. We made one mistake in defence – we don't make many mistakes in our defence – we made one, they got the penalty and the game was open.
“Then it was ‘okay, who gets the lucky punch and takes it’. Today it was Everton, last week we had the lucky punch, so that's football.
"Again, I've seen over 60-70 minutes, a fantastic performance from us."