What happened to sodas girlfriend and why in the book outsider?

There seems to be some confusion. There's no character named "Soda" in the book "The Outsiders" by S.E. Hinton. The protagonist is Ponyboy Curtis, and he has a brother named Darrel "Darry" Curtis and another brother named Sodapop Curtis.

While the book focuses on Ponyboy's personal struggles, his brothers' relationships, and the gang life, it doesn't mention Sodapop having a girlfriend.

If you are referring to a different book or another character, please provide more context.