Your friend experienced a negative event i.e. break up of an important relationship. You are trying to experience how your friend is feeling. You are trying to take her / his perspective of the entire situation. Identify the term used to refer to this :

Empathy

Empathy is present when one is able to understand the plight of another person, and feel like the other person. It means understanding things from the other person’s perspective, i.e. putting oneself in the other person’s shoes.