Why is the first "me" in the sentence?
The sentences doesn't make sense. I think it should be "sé que ellA me quiere", without the first me.
I think it's a typo. The sentence should read: "Se que el me quiere, pero nunca lo habia escrito"--"I know he loves me, but never had he wrote it."
It is all about the context. It is the same with any other language, you will always find that in different languages, words don't seem to make sense due to our usual english pronounceation.