The loss means England now face a cut-throat game against Australia on Friday at the MCG that has the potential to end the tournament for the loser.
There were no excuses offered by the England captain for Wednesday's loss to Ireland. They did not lament the rain, the ground conditions, or the decision to come off with England just five runs behind on DLS with 5.3 overs remaining.
Buttler instead said that England needed to cop the loss square on the chin and made no attempt to sweep it aside as just an unlucky break.
"I think you should let it hurt to be honest," Buttler said. "I think days like today are really, really disappointing and you've got to feel that. There's no point in saying let's sweep it under the carpet and move on. I think we've got to reflect. We've got to do it quickly obviously with a game very soon after. But today should hurt."
Buttler even made the frank admission that the loss hurt more because it was to Ireland. Despite the fact Ireland have now beaten England three times in internationals, including twice at World Cups, the England captain said they expected to win the game.
"There's certainly the expectation on us to win the game today," Buttler said. "I think we should be expecting to beat an Ireland team. We expected a tough challenge, but we should be expected to win that game. So of course, that adds extra disappointment. Whether you'd say we're favourites or not going into an Australia game is more of a different conversation. So, I think that adds extra hurt especially."
Buttler admitted England had everything in their favour after winning the toss with rain almost guaranteed to impact the game.
But they bowled poorly in the first 10 overs to allow Ireland to get away to a flying start. Player of the match Andrew Balbirnie, Paul Stirling and Lorcan Tucker piled up 92 for 1 after 10 overs despite Balbirnie starting sluggishly.
Chris Woakes erred badly with the new ball on a surface that offered plenty of swing and seam, missing both his lengths and lines consistently to concede 41 from three overs.
"Especially in the first 10 overs with the ball, I thought we were a long way short of the standards we set ourselves in the game before," Buttler said. "We let Ireland get away from us. I thought we dragged it back well in the second half, but that put a lot of pressure on us right from the start."
Ireland's seamers then showed their England counterparts up on the same surface prizing out Buttler, Alex Hales and Ben Stokes cheaply in the powerplay to leave England well behind the DLS target as dark clouds loomed over the Ponsford stand.
"I take full responsibility myself," Buttler said. "To lose wickets like that puts the pressure on. I thought Ireland showed us how to bowl on that wicket. They found movement and created problems. That's just a really disappointing day."
England nearly hauled it in thanks to some excellent late hitting from Moeen Ali as the rain began to fall. They were just five runs shy on DLS when the game was called off. Buttler had no issue with the umpires' decision to take the players off and stated that with the benefit of hindsight they could have used Ali and Liam Livingstone earlier to get ahead of the rate.
England have just 48 hours to turn it around. There is little margin for error now for Australia or England on Friday night at the MCG. But England have experienced this position before in the 2019 50-over World Cup.
"That's what World Cup cricket is about," Buttler said. "Of course, we wanted to be going into that game having won two games from two. But at some point in this tournament, the way it's set up, you're in must-win games the majority of the time.
"Friday's already a big occasion playing Australia at the MCG and it takes on that extra bit now with both teams having lost one game."
Alex Malcolm is an Associate Editor at ESPNcricinfo