Years out of college, he read that the part of the brain activated for love and the part activated for grief were quite close, physically. Love can be a type of euphoric grief, the author wrote. There are stages: self-delusion, understanding, and—most important—the obsession, in a different way than grief, with another person.

What we feel varies enormously from person to person, and may include many different emotions including anger, sadness, anxiety, guilt, loneliness, despair or fear. Such feelings are normal reactions to any significant loss, whether a loved one, a job or a limb; we expect to feel them as part of a normal grieving process.