WASHINGTON — Blame it on these bitter political times.

The feud over President Trump’s call to the widow of a fallen soldier might never have escalated had Mr. Trump done what any of his predecessors almost certainly would have done: quickly apologize for words that failed to bring comfort.

Likewise, the nasty back-and-forth with Frederica S. Wilson, a Democratic congresswoman who is close to the soldier’s family, might have dissipated had she not repeatedly disparaged Mr. Trump’s intentions on national television, failing to extend him the benefit of the doubt that previous presidents had received.

And the public relations disaster that engulfed the White House might have been less intense if John F. Kelly, the president’s chief of staff, had not publicly vented his anger at Ms. Wilson, calling her an “empty barrel” and incorrectly asserting that she had boasted about herself during a ceremony for a building named for fallen F.B.I. agents.

But the political guardrails that once could have prevented a soldier’s death from spiraling into a weeklong, made-for-TV spectacle have been wiped out by a mistrust that has deepened on all sides with the rise of Mr. Trump.