Where did I ever say it was always a good reason?

There are many possible reasons and sure, not all of them are good.

The point is if you tell others before knowing what her reason is to hide it, you just told her not to trust you again ever.

And if what you relayed was a comparatively small thing, you will never know when there is something big, actually more worthy of telling others. Because she will not bother to inform you.



Let's even use your non-sexual, non-drug example: what if she sees a neighbor bury a body?

It is useless to tell anyone.

Parents cannot do anything about it, good or bad, unlike the sexual or drugs examples.

Police do not have probable cause just because someone rang an anon call to 911. If it is not anon, her testimony will be thrown out by any good defence lawyer; but the traumatic court experience will remain; and after the testimony is thrown out, the search is invalid and has to be thrown out too, so the neighbor goes free, and is free to sue, harass or worse, her and her family. Because Ethan must tell. Though after that, of course, she will know better than tell you anything else.