so it goes
an expression showing regret used in two different occasions: Either when simple plans do not work out, or when the universe cosmically fucks you over. Vonnegut stole it from some french author, and popularized it in Slaughterhouse Five.
Example:
1.
"did you meet up with those kids?"
"No, they went home."
"ah, so it goes"
2.
"So you avoided hitting a deer while driving only to run into a tree?"
"Yes."
"So it goes."
1.
"did you meet up with those kids?"
"No, they went home."
"ah, so it goes"
2.
"So you avoided hitting a deer while driving only to run into a tree?"
"Yes."
"So it goes."