leave someone in the lurch
US /liːv ˈsʌm.wʌn ɪn ðə lɜrtʃ/
UK /liːv ˈsʌm.wʌn ɪn ðə lɜrtʃ/

1.
to abandon someone in a difficult situation without help
:
•
My partner left me in the lurch when he quit the project unexpectedly.
•
It's not fair to leave your friends in the lurch when they need your help.