Snipped
In the USA it only is an issue if it is a Republican having the affair. Those of Democrats are routinely ignored, not reported, and not considered in decisions about them.
To me it seems quite the opposite. Hillary Clinton was given grief how she was not a feminist because she did not leave her husband when HE had an affair. But Donald Trump gets to have affairs with porn starts and nothing happens.
What you say is partly true, but it went far beyond that. For Clinton there were numerous substantiated reports of rape and other serious allegations, in addition to the Lewinsky affair that basically led to the Starr investigation.
Hillary was largely complicit in all of that including defending her husband on the rape charges. Yes in the last two years, FINALLY, people have swung against her for that.
Trump has an number of consensual affairs. I am not seeing that his behavior now or in the past even approaches the sexual predator activities of Bill Clinton.