Yes!! Yes, it’s a real saint’s name! Hahahahahah! I am really delighted to find this out!
St. Blitha of Martham (also known as St. Blyth, Blythe, or Blida) was a laywoman in East Anglia. She was a kinswoman of the illfated King of the English, Aethelred the Unready, and of his son, King Edmund Ironside. She was married to a wealthy nobleman named Benedict. He had at least one son, St. Walstan, who moved to Taverham at the age of twelve and became an ordinary farm laborer, albeit a pious one.
Benedict and Blitha seem to have lived in either Blythburgh, Suffolk (which may have been her property, or may have changed its name in her honor) or in Bawburgh, Norfolk. But at the time of her death, after Benedict died, she was living in Martham, which is a lot further inland and somewhat closer to Taverham. A chapel was built in her honor in Martham.
The Old English word “blithe” or “blythe” meant friendly, agreeable, cheerful, kind, merciful, pleasing, gentle, pretty — basically, a lot of pleasant qualities. Its ultimate root means something like “shining.” It’s a great name — and now we know it’s a saint’s name! Great stuff!