Mockingjay is the third book in the Hunger Games Trilogy by Suzanne Collins. The impact and after effects of war are central to the themes of Mockingjay. Katniss Everdeen, the face of the rebellion against Snow, is so badly effected that she can never really function normally, despite eventually having children with Peeta. She reflects that "there are much worse games to play," knowing all to well the devastating impact it has had on her.
The resolution in any novel provides the reader with a conclusion when all loose ends are tied up, conflicts resolved and any major complications are clarified. Sometimes, when there is to be a sequel, there will be something left out that will only be resolved in the next book. In Mockingjay, Katniss is released and allowed to make a life for herself, which she does with Peeta. The fact that Gale moves away seems to leave unanswered questions but the ending suits the story which was never going to have a happily-ever-after resolution.
The reader must consider the effects of war, based on the fact that in this apparent internal battle of Man versus himself and versus society, so many people needed to die. The "changed" Katniss serves as a warning of the meaninglessness of war much like the ending of Mockingjay as she seems to just go through the motions. Her passion is lost. She is haunted and wonders who will "be joining the cast of my nightmares tonight" such is her acceptance of her lot. This allows the story to come towards its conclusion as Katniss' acceptance is part of her healing process. She wants "to make their deaths count." Solace is found as Peeta's "arms are there to comfort me." Peeta is her "dandelion in the spring" making it "real."