The 44-year-old Englishman admitted Ireland had been left a huge task once they went 17-0 behind by half-time.
England head coach Eddie Jones said if it had been a cricket match he might have declared at half-time.
The Irish did improve but never looked like adding to their wins against Scotland and Wales or sealing the Triple Crown and staying on course for a second Grand Slam in three years.
“I need to look at myself,” said Farrell at the post-match press conference.
“Really, were they more up for the match than us when we were going for the Triple Crown?”
Farrell, who experienced his first defeat since he replaced Joe Schmidt as head coach following last year’s World Cup, said he had had to ask the players if they were in the right frame of mind.
“I asked the players at half-time if they had self-belief,” said Farrell.
“How you get to be at your best is when you are winning collisions, and we came off second best for large periods of the first half.
“We should have expected them to come out fast and by doing so it allowed them to be on the front foot.”
Ireland captain Johnny Sexton’s off-colour performance in the first-half set the tone for the whole team.
The 34-year-old had been outstanding against Scotland and Wales but he never fired. His fumble presented George Ford with the first try and a rare miss of a kickable penalty were just two of Sexton’s slips.
‘Stuck in the same game’
Sexton said that Farrell should not blame himself for under-preparing the team.
“Faz will always say that,” said Sexton. “As players we were in the right frame of mind.
“I did not deal well with the chip through that led to us being 7-0 down and then ditto we did not cope with another chip through for 14-0.
“However, I was proud of the lads in the second-half, but we were always chasing.
“We had a brilliant preparation but in the end the difference between victory and defeat like that is very small.”
Sexton, who played throughout with thick strapping round his right thigh, said he had felt a sense of deja vu from last year’s 30-22 loss to England which ended their hopes of a repeat Grand Slam.
“Very similar game-wise to last year’s match in Dublin,’ said Sexton.
“The chip through early on, it was like being stuck in the same game.
“When we did have the ball they shut us down well.
“We were going backwards when we had possession and we need to get rid of the ball not over play it.”
Farrell refused to blame Jacob Stockdale either for the second try when the winger was out-muscled by Elliot Daly to Ford’s chip through.
“It is important the bounce of the ball and it went right and threw him off.
“I would probably look at why they were doing that in the first place.
“That was because the high balls they put up early on they gained easy access.
“You have to deal with things that don’t go your way like the bounce but also look at the bigger picture.”
Sexton said he had not taken the final kick of the game, a conversion for a late try, as he wanted to get the players in a huddle and tell them a few home truths.
He did sound an upbeat note.
“We are still in the competition,” he said looking forward to the next two matches.
“If we can do the job against Italy with a good performance we will be in with a shout of the championship for the final match against France in Paris.
“However, it is not in our control now which is a shame.”