someone's heart sinks
A:Do you feel better?
A:你觉得好点了吗?B:Much better. My heart sank when Mary told me that she wanted to leave me.
B:好多了，当玛丽告诉我她要离开时，我的心为之一沉。
A:Don't be sad. Everything will be fine.
A:别伤心，一切都会好起来的。B:Thanks a lot. You're so kind.
B:多谢了，你真好。