Greig, Charlotte. A Girl’s Guide to Modern European Philosophy.
Samantha, working on her dissertation in philosophy, uses lessons from Nietzsche and Kierkegaard to direct her actions, namely, beginning an affair with her classmate, even though she lives with a boyfriend 10 years her senior. Then she gets knocked up.
Set in the swinging 70s, she might be a poster child for women’s lib; the writing is a little dense, and the protagonist is not a particularly sympathetic character.