This article is written from the perspective of the person who initiated the breakup. The one who gave up and walked away.
The person who was left behind, who did not want to end the relationship, also idealizes the past.
But they cannot go back and revisit their reasons for ending things. Perhaps they were happy in their bubble of ignorance? Perhaps they loved their partner enough to overlook or accept their flaws? In any case, the decision to end the relationship was not theirs and not mutual. They were the one abandoned and their past looks a lot more appealing than their present.
If you had to re-write this article for the dumpee, the one person in the relationship often shocked and surprised that their partner was dissatisfied enough to give up and go, what would you say?