When Naami leaves Moav to return to Israel, the Megilah mentions that she left the fields of Moav, and went to Israel. In order to indicate that Naami's departure made a tangible impact on that location. Naami was of such righteousness that her departure was significant for Moav. Leaving Israel Naami, along with her family, abandoned Israel to head for Moav in a time of famine. HaShem was angry that they left, and punished them with the death of Elimelech, as well as that of Naami's sons.
Similar statements appear in various Midrashim.
Their departure had too great an impact on those around them. He explains that Naami didn't necessarily want to go. Elimelech bullied her into going along, and so she was not directly responsible. The second view is that Naami was complicit in the act, despite her righteousness. Naami's Suffering Naami suffered greatly as a result of their departure from Israel.