Example : Her smile betrayed her true feelings.

Synonyms : bewray

Example : Judas sold Jesus.
The spy betrayed his country.

Synonyms : sell

Example : His sense of smell failed him this time.
His strength finally failed him.
His children failed him in the crisis.

Synonyms : fail

Example : She cheats on her husband.
Might her husband be wandering?.

Synonyms : cheat, cheat on, cuckold, wander

Example : He told on his classmate who had cheated on the exam.

Synonyms : denounce, give away, grass, rat, shit, shop, snitch, stag, tell on

Example : The insurance company deceived me when they told me they were covering my house.

Synonyms : deceive, lead astray