Many of us ask the question, "why should we trust someone/anyone who has broken the vows of their marriage?" Sure, Reagan was divorced himself, but you have people like Rush & Trump with 3 or more marriages each.
In today's world, one divorce gets most a mulligan. More than that is a serious character flaw. IMO, of course. Rush hasn't been on the cutting edge of societal evolution since he started selling Marta's scarves. He sures loves Trump...blech.
I'm not really concerned about the simple issues of broken vows of marriage concept because they are only as good as the person making the vow and for most, it is tradition, not contractual in a legal or moral sense....
... what I'm concerned with more is the same concern many had with Bill Clinton. When someone plays around as much as they both have (and Trump bragged about it a lot), that leaves him very open to blackmail and extortion.
Trump's advantage on the subject though is he doesn't deny it. He brags about it. He bragged he got more tail than Hugh Hefner. So nothing coming out of the woodwork would be a surprise, even a few little orange illegitimate ones.