Collocations for resentful - adj.

be, feel, look, seem, sound | become, grow
They grew bitter and resentful.

remain

bitterly, deeply, extremely, very
They were bitterly resentful of the fact that they had to work such long hours.

increasingly | almost
She looked at him, almost resentful now.

a little, slightly, vaguely | secretly

about/at
She felt resentful at the way she had been treated.

of
He was very resentful of their success.

towards
He felt deeply resentful towards his ex-wife.