리라고

That it would turn out so

It quotes a prediction inside a bigger sentence, and in every line here it is followed by a verb of thinking or saying: I could not have imagined it would come this far, I do not think he will show me a better solution, I am sure you all know the reason. The surrounding sentence is usually negative or about expectation, because the whole point is marking what someone did or did not foresee. It is the archaic 리라 with the quoting 고 attached.

Register: neutral to formal