Is Donald Trump acting as he does to ensure that Hilary is elected?

He's acting like a spoiled child with a severe personality disorder. This has become personal now, and will never admit to losing through his own failings. Notice that he's already preparing his followers for the inevitable drubbing by claiming that the election is "rigged" He's blaming the "media" and the Democrats when it's been Republicans that have been trying to rig votes in their own favour.

I dont see how defending your reputation, telling the truth about how unethical your opponent is, pointing to her disastrous history in government, criticizing the corrupt political system, is ensuring Hillary's election.

No. He's just not very good at this. That should have been obvious from the beginning.

It seems so...

Trump has turned into a Lunatic...

Yes, he is acting highly unstable. No logical person would vote for him.

Sure seems like it. He should endorse her.

can't understand why his detractors would feel that way ...

no