From the book One Day

Okay, a lot has happened at this point in the story. Emma breaks up with her live-in boyfriend after he proposes marriage to her. This leaves the live-in boyfriend (Ian) totally devastated and he finds it hard to move on. Then she starts up a year long relationship with her boss who is a married man. She breaks off with him because she's not in love with him. Her boss is angry with her because she doesn't want to continue the affair anymore. She winds up quitting her job at the school after failed attempts to get her book published which she realizes is now her true passion.

Let me say this, if I were in Emma's shoes, first, I would not date my boss or a guy I didn't love. These two guys are crazy about her and it is as if she used them to pass the time waiting for Dexter. She's not thinking in terms of the long run. She's thinking in terms of good-for-right-now in her decisions to date a guy. Dexter is the one she secretly loves but he does not feel the same way about her. He is in love with another woman. The whole thing is just a mess. So classic!