fizzle out
US /ˈfɪz.əl aʊt/
UK /ˈfɪz.əl aʊt/

1.
desvanecer-se, fracassar, esmorecer
to end or fail in a weak or disappointing way after a promising start
:
•
The protest movement seemed to fizzle out after a few weeks.
O movimento de protesto pareceu desvanecer-se depois de algumas semanas.
•
Their initial enthusiasm for the project began to fizzle out.
O entusiasmo inicial deles pelo projeto começou a desvanecer-se.