Ireland captain Rory Best called for more from his side after England extended their winless Six Nations run to three games.
England won 21-10 at Twickenham on Saturday, leaving defending champions Ireland with just one point after their draw with Wales and defeat to France.
Ireland were resolute in defence in the first half and scored the game's opening try after 46 minutes, but two tries either side of the hour mark saw England pull away.
"We're obviously bitterly disappointed, it's something that we not used to losing in an Ireland shirt and it hurts," Best told the Irish Rugby Union website.
"There's a lot of effort put in and character shown, but ultimately effort and character doesn't win you Test matches.
"You've got to be better in that final quarter of the pitch, and I think yet again we let too many chances slip by.
"We absorbed a lot of pressure, the boys stood up and we were defensively very strong in the first half, but ultimately we just let a few slip by and when they got a go we let them score those two tries a bit too easy for our liking."
Coach Joe Schmidt blamed tiredness for another frustrating night for his side, but remains confident they can turn their fortunes around in the final two matches.
"We let them come back at us. There was a bit of fatigue and it was disappointing to lose the lead after being 10-6 up," he told a news conference.
"It was an evening of frustration. There were some positives for us and we need to make sure we get a result. The team showed real enterprise and character. We have to get better at converting opportunities which will come with experience.
"We're in a transition period. Don't lose faith that we won't keep building."