Newcastle have now lost a staggering 25 points from winning positions in the Premier League this season, which Howe described as a "crazy statistic".
Three points were thrown away at Selhurst Park on Sunday after Jean-Philippe Mateta came off the bench to score a late double and fire Crystal Palace to a comeback victory against the Magpies, who had led at half-time thanks to Will Osula's opener.
The defeat leaves Newcastle 14th in the Premier League and piled further pressure on Howe, with Newcastle's hopes of qualifying for Europe next season fading fast.
"It's really disappointing again," said the head coach.
"We worked so hard to get into a positive position. We played really well in the first half to be leading the game. There was a lot of the performance I was pleased with,
"But at the end of the game we didn't defend well enough for 20 minutes, albeit they didn't have a lot of chances. It's uncharacteristic of us going on past history to defend like that. We're desperately disappointed."
Newcastle's game management has repeatedly let them down this season, which has led to so many points being blown from winning positions.
Howe said: "It's a crazy statistic and I have no idea where that's come from.
"It's something that's blighted our season all year when we've worked so hard. For me it's the hardest thing to do to get in the lead, to implement your plan and gain the momentum to score. You saw how hard we had to work for the goal.
"There's a feeling we have gifted our opponents goals at bad moments. It's affected our psychology and it's clear to see we're struggling in that aspect at the moment.
"Sometimes these things just happen and you work your way out of it and then hopefully that can become a positive because you've learnt from previous mistakes.
"I don't know if it's because we're preoccupied with the result and we're desperate to win so much that it's impacted us negatively. I think it's a difficult one to define where the issue is other than to say it is clearly psychological."
Palace's winner came from the penalty spot after Sven Botman was spotted pulling the shirt of Jefferson Lerma.
Howe said: "I feel it was soft but once the referee gives it I don't think he's going to overturn it.
"Sven has grabbed his shirt. There's not a lot in it but it's given and that's a hugely disappointing end to the game.
"It was so late and there was so little time to do anything about it. It's a goal we've gifted them."