I've noticed this all of a sudden. Byron-King was countess of Lovelace, but everyone seems to be using Lovelace as her last name now. It seems strange to me, like calling Kate Middleton-Windsor, duchess of Cambridge, Kate Cambridge. Is there any idea as to why this is?
A countess is properly addressed as “Lady” and title, not by last name. Her family called her Ada, so she would be introduced as Lady Ada Byron-King, Countess Lovelace.
Her father was George Gordon Byron, Lord Byron, but he’s usually referred to simply as Byron.
At some point “Ada Lovelace” stuck as the common way to refer to Lady Lovelace. I have never seen her referred to as Augusta Ada Byron-King.
>I have never seen her referred to as Augusta Ada Byron-King
In the sources I've seen, they sometimes leave off the King, but Byron is often there. One of the most popular would have been the Windows 95 certificates of authenticity (she's there, with her name, as a watermark). Here's the clearest one I could find (blurry, but you can make it out mostly): https://files.catbox.moe/aci1d6.png - you can see it if you zoom in just above the "Product ID" text.
Regarding the first name: Lord Byron, the Romantic period poet, was known to have close relations (almost certainly incestuous) with his half sister Augusta Leigh. Augusta Ada was named after her, but she went by Ada for reasons of propriety, jealousy, etc.
Her father was George Gordon Byron, Lord Byron, but he’s usually referred to simply as Byron.
At some point “Ada Lovelace” stuck as the common way to refer to Lady Lovelace. I have never seen her referred to as Augusta Ada Byron-King.