Plants with big leaves can sometimes suffer a broken midrib. This seems bad, but it's treatable.

This nepenthes had a couple of injured leaves when I adopted it, and they couldn't support their own weight properly.

If this happens, put something nearby to rest the plant's leaf on. An upturned teacup works fine. Support the leaf for a few days, so it can heal.

The leaf in this photo will always have a scarred midrib, but it's otherwise healthy now!