I don't disagree with you regarding the likelyhood of a misreporting or faulty memory in reporting these dates to the clerk.Not being from the east, I am unsure how records were reproduced back that far.I am sure we can agree that record-keeping was low priority for our ancestors for the first twenty to thirty years of New England.At least that is what the derth of records hints at.Even if it was, early records were easily lost in fires and other disasters in those first few years.
In any case, I have no mention of Nicholas and Martha being married in Springfield.To me, that would have been foolish as both parties were residing in Rehoboth at the time and had a prominent minister available to perform the cerimony (of course there is always the case that marriage in those days was a civil, not a religious, matter).I have relied heavily on the Elith Flanders Dunbar Genealogy of the Ide Family as published in "Simon Ide, Yeoman, Freeman, Pioneer Printer," by Louis W. Flanders, M.D. published by the Turtle Company in Rutland, VT, 1931 as microfilmed by the Iowa State Historical Society (#5478-94) available through the LDS family history centers.I have looked more recently at the Schenectady Digital History Archive for the Ide family and find no discrempency.
I do envy you for your access to colonial records as this beknighted state I live in does not thing anything exists east of Utah!
Another theory has occured to me; one I think could explain all the issues but, of course, it can'tbe proven.
Suppose Nicholas Ide was married about 1645, when he drew for land lots in Rehoboth and had a son, Nathaniel.The mother dies, perhaps in childbirth, and Ide marries, for his second wife, Martha Bliss.Nathaniel gets mentioned in Bliss' will but dies before his half-brother, named Nathaiel in memory, is born in November of 1647.
While requiring two assumptions, this does seem the most simple explanation.