I have a similar story but it ends differently. I dated a girl in college who was #1 in her high school. Similar to your ex, she studied like crazy, and extended studying sessions without end were routine. She proceeded with college in the same way; and while it worked for the first ~2 years, she was completely burnt out and exhausted by graduation time, leaving her deeply depressed. While she had always intended on going to grad school, she instead gave up on that and is now working in a low paying, low intellectual demand manual job.

I'm not sure what the moral of the story is.