understatement of the year ! - I'd start with the parish reg film which includes marriage to see what (if any) additional information is present (eg witnesses), have you found the burial and any census entry for either partner - these may give some info, any MI? If still a blank then date of last known child is very seldom post age 45 and usually nearer 40 - the marriage should have (no guarantee however) indicated if either/both were minors.
Use the parish reg rather than the igi - Kewleys have been messed up in igi (several entries are wrong + others have been assigned to wrong partner (the original entry would not have given wife's name for some years in Braddan