water under the bridge

(idiom) something in the past cannot be fixed, so it must be forgiven

Example Sentences:

Best Friend 1: Hey man.
Best Friend 2: Hi.
Best Friend 1: Look, I want to tell you something. Two years ago I went on a date with your wife.
Best Friend 2: I know, she told me.
Best Friend 1: I’m so sorry. I must apologize.
Best Friend 2: It’s water under the bridge.
Best Friend 1: Why?
Best Friend 2: Because I went on a date with your wife!

My mother tried to apologize for being cruel to me when I was a teenager, but I told her it was water under the bridge and she could forget about it.

From the Blogs:

When Giants Fail: No Water Under the Bridge

Media:

Similar idioms:

1. forgive and forget
2. let it slide
3. does not hold water
4. get into hot water
5. epic fail
6. check in with
7. throw cold water on
8. fish out of water
9. blood is thicker than water
10. lead someone on
11. hold one’s tongue
12. keep one’s head above water