The Titans' skipper was given his marching orders for repeated infringements in the 62nd minute of the clash at Robina's sold-out CBUS Super Stadium on Saturday.
In his absence, the Broncos ran in two tries and kicked a penalty goal to stretch their lead from eight points to 22 before going on to claim a 43-26 victory.
"It's just frustrating," Fa'asuamaleaui said.
"I let the team down, you know? Crucial moment like that where we were on the backfoot and then I sort of let the team down by getting sent to the bin.
"That made it hard on the boys with 12 men - and that's when the floodgates opened.
"I've just got to be better as a leader, as a captain and not get sent off from something stupid."
Saturday's match marked the return of veteran Kieran Foran to the Titans' halves and, with Jayden Campbell performing well at fullback, Gold Coast coach Justin Holbrook admits he'll face a selection dilemma when AJ Brimson returns from a hamstring injury.
Brimson is expected to be fit for next week's clash with the Dolphins at Suncorp Stadium, meaning one of Campbell, Foran or halfback Tanah Boyd would need to make way for the former Queensland State of Origin representative.
"I'm not too sure. Hopefully, AJ will be back next week and then I'll sort of worry about it then," Holbrook said.
"It's a good headache to have, we need good players.
"We probably missed AJ tonight in different parts of the game.
"We'll fit them all in. We just need them back. We've still got some troops missing, so we've got to get them back."
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