Catholic dispensations

A dispensation would be needed if the husband and wife were considered too closely related.  For Catholics, in more modern times, that usually means being within four degrees of consanguinity (meaning that second cousins could marry), but in the Middle Ages it was broader, covering seven degrees of consanguinity (meaning that second cousins could not marry).  A complication in some rural places in Ireland, with local families who had been intermarrying for generations, was how to calculate the relationship, since the couple might be related in several different ways, through different branches of their families (and might even have the same surname).  Catholic parish registers often show an actual calculation by which the priest figured it all out, but I've usually seen that written right into the record for the marriage.  Different priests took different approaches, though.

If the baptismal records for the children are in a different parish, that may mean that the wife was from the parish where the wedding took place, but the husband was not.  Weddings usually took place in the bride's parish, and the couple may then have gone back to live in the husband's parish, and raised their children there.