Use 'fizzle out' to describe something that diminishes slowly, not abruptly.

Gradual Decline

Suggests an ending that is less exciting or successful than expected.

Lackluster Ending

Indicates a process or effort that does not achieve its intended goal.

'Fizzle out' does not mean an immediate stop; it’s a gradual process.

Can describe feelings or excitement that vanish over time.

Refers to something that concludes without reaching a satisfying or expected climax.

Means that once it starts to 'fizzle out', it typically doesn't pick back up.