The Dockers' finals hopes are on thin ice after they crashed to 14th with their fourth loss in five games.
The lack of fight displayed against Carlton was a major talking point after Sunday's match, with the Blues winning the clearance battle 42-35 despite losing the hit-outs 70-18.
The Blues kicked eight consecutive goals either side of halftime to open a 64-point lead by the final change.
Such was the discontent in the 49,469-strong crowd, some Dockers fans booed their own players at three-quarter time.
Fremantle's task becomes still harder this week, with the Dockers facing ladder leaders Collingwood at the MCG on Saturday in a repeat of last year's semi-final.
Longmuir is urging his players to move on quickly from the disappointing loss to Carlton.
"Don't wallow in your own self pity," Longmuir said.
"We're all disappointed. But we've got six days' lead-up to a great challenge.
"So we need to get around each other. We need to help each other get better and we need to bounce back."
The third quarter against Carlton was particularly brutal as the Blues slammed through six goals to nil to ice the game.
"Definitely in that third quarter we internalised, got stuck in our own heads," Longmuir said.
"The scoreboard got out of control, players would have been worried about their own form, and we just went away from any resemblance of a connected brand.
"We spoke about that at three-quarter time and it was better in the last quarter.
"You've got to fight through momentum as a team, you can't fight through it individually. We tried to fight individual battles rather than connecting as a team."
Longmuir doesn't think his players gave up.
"No one gives up. It's just you internalise in those moments and it looks like you just become disconnected and that's what happens," he said.
"We went about it the wrong way and we needed players to be the glue in those moments and we just didn't have enough.
"We will keep educating our players and talking through those situations during the week."
Fremantle (7-9) will probably need to win six of their last seven games to sneak into the finals.
But with a run home including games against Collingwood (away), Geelong (away), Brisbane (home) and Port Adelaide (home), Fremantle face an uphill battle.
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