Your assessment is RIGHT ON!
Before and during the 19th century, it was not frowned upon considered immoral, or unusual for 18-19 year old young women to be married to slightly older men regardless of political views, and even across New England USA.
It was not average, but it was not unusual at all.
Life expectancy was dramatically less than today!
Today, moral boundaries have fallen, and most individuals are not spiritually or morally grounded. At the same time, children and young adults across society today are much more protected.
As a result, young adults have not had to learn to survive, or carry the true adult stress and maturity of past generations.
While there are clear moral limitations, in my opinion, it is a truly false and gross historical illiteracy which cannot grasp recent generational norms, because of current norms and bias.
I see this problem whenever disputes arise from different eras, especially the wider the time differentials between the period in question and the present.
The past really is a "foreign country" to some. They can't grasp how things were not always as they now see them. They don't understand this concept of "Zeitgeist."
It makes it difficult to get through to them about differing cultures in the past. It makes it hard to get them to understand how we got to where we are now, from where we were before.