What is the "mistake" that caused Doug Loverro to resign as NASA's Human SpaceflightChief so shortly before DM-2?

Question

Today, on May 19, 2020, Doug Loverro announced his resignation. It's a bizarre time to do so, so shortly before the Commerical Crew Program puts astronauts into space for the first time, but even stranger to me is his resignation letter:

Team HEO

On December 2nd of last year, day 1856 in my pin count, it was my privilege to become your Associate Administrator for Human Exploration and Operations. That was a time before we were in the final count for the first crewed flight from American soil in nearly a decade; before we brought on board three industry partners to propel our lunar dreams and ambitions; before we took on the task to reorganize ourselves for the future and the adventures that lay ahead; before COVID-19 and endless hours of telework that would test our spirit yet prove our mettle; and before we knew for sure that we could fulfill the promise we made to the nation to meet its 2024 goal. But now, a mere 168 days later, all those things are no longer in doubt.

The day I joined NASA and this very special directorate was one of incredible joy for me and my family. I was humbled by the confidence that had been placed in me by the Administrator and honored by your acceptance of this new unknown leader from the outside. Over the past short six months as you have come to know me, I have come to know you too – I now can count many of you as not just co-workers, but, truly, as friends. It has been the pleasure of a lifetime. I want to let you now that I had truly looked forward to living the next four-plus years with you as we returned Americans to the surface of the moon and prepared for the long journey beyond. But that is not to be.

Throughout my long government career of over four and a half decades I have always found it to be true that we are sometimes, as leaders, called on to take risks. Our mission is certainly not easy, nor for the faint of heart, and risk-taking is part of the job description. The risks we take, whether technical, political, or personal, all have potential consequences if we judge them incorrectly. I took such a risk earlier in the year because I judged it necessary to fulfill our mission. Now, over the balance of time, it is clear that I made a mistake in that choice for which I alone must bear the consequences. And therefore, it is with a very, very heavy heart that I write to you today to let you know that I have resigned from NASA effective May 18th, 2020.

I want to be clear that the fact that I am taking this step has nothing to do with your performance as an organization nor with the plans we have placed in motion to fulfill our mission. If anything, your performance and those plans make everything we have worked for over the past six months more attainable and more certain than ever before. My leaving is because of my personal actions, not anything we have accomplished together.

While there are no guarantees of success, I know, and agency leadership knows, that you are in the best position we have ever been to accomplish our goals. The plan we have placed in motion, the new HEO organizational structure we are putting in place, and the leadership team we have brought on board all give us the opportunity to show again just what the people at NASA can do – and it will inspire the nation just we have before.

I cannot say what happens next. That will be for others to decide. What I can tell you is that you have a team of extraordinary leaders in Ken Bowersox, Toni Mumford, and all the other DAAs and seniors in HEO. I can also tell you that HEO is populated by a host of HERO’es, some publicly acknowledged but many just performing every day. I know that together you will make the impossible happen. And that in just over four years from now, I will look up at the sky, and see the moon rise for the first time in this century, secure in the knowledge that Americans are there to stay.

Doug

To the Moon, Mars, and the Stars Beyond

Farewell

Emphasis mine. Doug refers to a "risk", a "mistake", and his "personal actions".

What did Loverro do?

Answer 1

According to the Washington Post, Doug Loverro shared internal information regarding the commercial lunar lander contracts with Boeing, who then tried to amend their bid over the contract for the lander. This led to concerns Loverro improperly sharing the information and giving Boeing an unfair advantage, and Loverro was asked to resign.

Due to the article stating that this is what led to Loverro's resignation, and that Loverro stated that he is resigning due to a personal action, it is likely that his personal action that he described as a mistake and a risk was to share information to Boeing in a non-standard way that was potentially in violation of the restriction that NASA places on its employees with communicating with potential contractors, to keep the bidding process fair.

Source: https://www.washingtonpost.com/technology/2020/06/20/nasa-boeing-bid-probe/

EDIT: I want to clarify that this contract has nothing to do with the Commercial Crew Contracts that will take astronauts to the International Space Station, and was not placing them, or any astronauts on active missions, in immediate danger.

2nd EDIT: This article on ArsTechnica has brought some further information regarding what happened. Apparently Loverro informed Boeing that they were about to be eliminated from the competition as their proposal was not considered a good one. Boeing then used this information to submit a new proposal to NASA. Other employees at NASA recognized that they must have received insider information and notified the inspector general, as during the bidding process, any sort of assistance to a single entrant by providing additional information is illegal. As a matter of fact, a grand jury is now investigating Loverro, and may decide to charge him criminally.