Final answer:
Rationalization is the defense mechanism that best explains focusing on the financial implications after a sudden breakup.
Step-by-step explanation:
The defense mechanism that best explains focusing on the financial implications after a sudden breakup is rationalization. Rationalization is a defense mechanism where a person justifies their behavior by substituting acceptable reasons for less-acceptable real reasons. In this case, focusing on the financial implications allows the person to avoid dealing with the emotional pain of the breakup by shifting the focus to practical concerns. For example, they may tell themselves that they need to focus on their finances now and that it's better for them in the long run.