Tomorrow, and Tomorrow, and Tomorrow By Gabrielle Zevin

The primary story line follows three friends over many years and places (Boston to LA to Tokyo) as they play video games together and then create them. The two main characters— Sam and Sadie— have a volatile friendship— cyclical love/hate relationship. The third character— Marx— acts as the neutralizer and stabilize. 

A Quote:

“The way to turn an ex-lover into a friend is to never stop loving them, to know that when one phase of a relationship ends it can transform into something else. It is to acknowledge that love is both a constant and a variable at the same time.”