a sudden change from something exciting or important to something much less exciting or important (causing disappointment)

ineffective conclusion

the sudden change from something interesting, noble etc to something ridiculous or insincere (often deliberately for humorous effect)

sentimentality

a period of gradual and continued loss of importance, strength

lessening

the loss of respect, favour, good reputation

state of shame; bad reputation

a heavy fall (of rain etc)

disgrace, ruin

a complete defeat and disorderly retreat

overwhelming defeat