Where is the evidence that the cause of the radioactivity and cuddling happened at the same time?
Quite simply, the city was built near a location which had radioactivity due to an ancient meteor hit.
Maybe the lingering, low-level radioactivity had some weird effect on people/things and it was a favorite/ritual gathering place because of it.
Twice?
there are some Hindu texts that could be interpreted to suggest there was a great war. God knows.