Sometimes President Trump violates the Constitution.
Robert Mueller detailed instances of Trump obstructing justice. He declined to accuse Trump of the crime since the Justice Department’s policy precluded prosecution. He left action to Congress, which did not pick him up on it. Trump makes money dealing with foreign powers. He makes money as the United States overpays for the use of his hotels. He violates the emolument clause with one; laws governing self-dealing with the other. Congress has not taken him up on it. He violated the constitution by distorting American foreign policy toward his own ends in Ukraine. He violated the constitution by obstructing Congress, refusing to provide documents and prohibiting testimony. Republican Members of Congress opposed impeachment and Republican Senators, with a single exception, voted to acquit him.
Nevertheless, the President is not acknowledged to be so powerful in foreign policy that he can do whatever he wants. The behaviors the House of Representatives took up and those the House did not take up, are appropriate for impeachment. If Trump is reelected, there will be more reckoning to come.