彼はすぐにかっとなる。

he; him; his; boyfriend

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

immediately; at once; directly; soon; before long; shortly; easily; without difficulty; right (near); nearby; just (handy)

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

flaring up; burning hotly; suddenly becoming bright; flying into a rage; losing one's cool; opening suddenly and widely (e.g. eyes, mouth); acting resolutely

to become; to get; to grow; to be; to reach; to attain; to result in; to prove to be; to consist of; to be composed of; to succeed; to be complete; to change into; to be exchanged for; to play a role; to be promoted; to do ...