The defeat, which saw Forfar 4-1 down at half-time, brought to an end what has been an excellent run of form for the Angus club.
It was compounded further by Kelty Hearts loss at Annan, Forfar blowing the chance to claw back ground on the league leaders.
“It was a weird feeling after the game,” said Irvine post-match to the club’s social media channel.
“In the second-half we just lacked that last bit of quality to get the ball in the back of the net a third time.
"We had our chances though.
"One fell to Steven Doris and there was another when the ball was bouncing about in the box after a set-play. We had a few good deliveries right on top of their keeper. So that was frustrating.
“It may sound daft, but all I could say to the players at the end was how positive the second-half had been.
"But I want them to hurt after this. I want them to want to win every game.
"I want them to take positives from this and that is how they approached the second-half. They knew the first-half wasn’t good enough though.
"They knew that was way below our standards.”
Forfar now prepare for a trip to Elgin on January 2.
“Elgin next week is another tough one,” added Irvine. “We had a hard time with them up there last time. We’ll work hard in training this week and look to rectify what went wrong. We need to get back on track.”