a world save isnt sufficient to prove it though, in a world save it could have been made, by your "friend" or someone else, to go to the nether.
If you enter the nether, build a new portal somewhere, it can generate a new portal in the over world. so you can exit.
If you move one block on the nether portal in the nether, it sometimes generate a new one, im not even gonne download the world save, but nobody here said there was one on the world seed yet.
And the reason you dont post it makes me doubt it more.
Destroy a nether portal, with someone in it, and a new one will be "naturally" generated when they exit.
This is in no way meant offensive against you, nor your friend. but someone made it generate there, or build it.
