jumping to a hasty conclusion, get ahead of oneself

to get ahead of oneself

anger, fury

to scold / to get angry, to anger

to get angry, to anger / to be shaped roughly / to go rumble, to behave roughly

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

(と〜) thinking that […] (with the next clause explaining that the truth is contrary to expectations)

to seem, to appear