fall through
US /fɔːl θruː/
UK /fɔːl θruː/

1.
fail to materialize; be unsuccessful
:
•
Our plans to go on vacation fell through at the last minute.
•
The deal might fall through if we don't act quickly.
2.
to drop or break through a surface
:
•
The old bridge might fall through if too many cars cross it.
•
Be careful not to fall through the thin ice.