I both agree and disagree with the photo. I don't think revenge is the right way to go as it won't solve anything or cause the pain to go away. It will more than likely make the pain worse. But I don't think we are called the "understand their situation" as that implies that had they been in a different situation they would have acted differently, which may or may not be true. It sounds like a way to take responsibility for their hurtful actions away from the person.
At the end of the day, they did something hurtful, and it's not up to the one who is hurt to justify the hurtful action. In fact, if all you do is justify the hurtful action, there is no need for forgiveness. I believe the true course to healing is to hold the person responsible for their actions and work to forgive them.