Verb
(idiomatic) To worsen a conflict between people; to inflame an already tense situation.
Synonyms: add insult to injury, fan the flames; see also Thesaurus:make matters worse
Antonyms: pour oil on troubled waters, clear the air
Instead of apologizing to his girlfriend, he decided to add fuel to the fire.
Used other than figuratively or idiomatically: see add, fuel, fire.
Source: en.wiktionary.org