怨恨 (yuàn hèn): to resent; to harbor a grudge against; to loathe; resentment; rancor

My younger brother has always resented our parents for sending him to boarding school back then, feeling they didn't love him enough.

She resents herself for not having the courage to refuse that marriage back then, and regrets it for the rest of her life.

Even if you resent your boss for being unfair, you shouldn't lose your temper at him in public during the meeting.

Many years have passed, but he still resents the friend who betrayed him and refuses to forgive.

She hid her resentment in her heart and remained polite to her stepmother on the surface.