Origin of ending a sentence with a preposition-German separable verbs?

Answer 1

It sounds like you're asking about the English grammar rule not to end a sentence (or clause) in a preposition - this is not related to German separable verbs. Let's compare.

The "don't end a sentence in a preposition" rule of English grammar has to do with something called prescriptivism: although English was already a fully formed language in the 18th century, scholars inspired by classical languages like Greek and Latin scrutinized the spelling and grammar and made up rules to enforce that made it sound more elegant to them - basically arbitrary and completely unnecessary. This specific rule can be traced back to a guy named John Dryden, who seems to have preferred prepositions in prepositional phrases instead of alone at the end of sentences ("stranded," "dangling," or "hanging prepositions").

German separable verbs, in contrast, are a linguistic feature fully accepted by descriptivists and prescriptivists alike - the preposition is a prefix and part of the verb and therefore considered a verbal phrase, not a stranded, dangling, or hanging preposition. Moreover, it was not in this culture that this rule was made, so it would not have applied.