Schenker was shy, spoke no English at all, was only 17 and came from a sheltered, if not wealthy background. The UFO guys were hard drinkers and partyers, came from an English blue collar background and physical violence was not unheard of among them. The first departure of Schenker was fuelled by physical violence of Mogg - he sucker punched Schenker backstage after an argument even though Schenker had said he would immediately leave the band "if Phil ever hits me". Mogg apologized, Schenker returned, but of course it happened again.
I know, Krauts are pussies.