Book from 1980s/1990s - hero tries to get a mysterious portal to release his love


Possibly a Darkfriend
Many years ago (at least 20 years past), I remember reading a fantasy book that I believe was the first in a series. It had something to do with a codex (I think?) and there was a strange portal of some sort into which the hero's love interest fell. The hero then spent some time yelling things at the portal which caused it to spit out various things but he wasn't able to recover his love interest. I think the book ended with the hero deciding to travel the world to try to learn more about the portal so he could recover his lost love.

I believe I read it when I was in high school, so anywhere from 1989-1993.

I'm fairly certain it's not the Codex Alera series by Jim Butcher. They didn't come out until after 2000 and the book I read was released either in the late 80s or early 90s. Anybody have any idea what this book title and/or author might be?