Blythburgh is in Suffolk - contact the County Archive.
Suffolk Record Office seems to have two general
References for their collections:- Number: FAA/23 Covering Dates: 1663-1859
Description:
FAA:50/2/77 marriage licence bonds 1663 - 1678
Sometimes the Genealogical Society (SofG / SOG) has some items filmed for various counties, but they charge too I believe.
I think Lambeth Palace Archives hold some too?
Some Registers of Marriages make no mention of Widower or Widow, occupation, nor age, so the Licence Allegations and Bonds can be highly useful for this information.
https://www.suffolkarchives.co.uk/collections/Mark