Echo on April 25, 2013 | reply

忘恩负义 is talking about someone who's ungrateful to people who have helped him. 过河拆桥 is not only ungrateful, but also does bad things to the one who helped you: he crosses the river, and burns the bridge.

--Echo

echo@popupchinese.com

murrayjames on April 25, 2013 | reply

Thanks Echo!

shawky.nasr on April 25, 2013 | reply

wàng ēn fù yì

ungratefulness

bite the hands that feeds one

【解释】忘记别人对自己的好处，反而做出对不起别人的事。

过河拆桥

guò hé chāi qiáo

比喻达到目的后，就把帮助过自己的人一脚踢开。

1. kick down the ladder

2. drop one's benefactor as soon as his help is not required

@Shawky Nasr