In the end, Katniss and Gale grew apart, as many childhood friends and young loves do. She needed something different in her life, and with Gale's link to Primrose's death, Katniss found a reason to cut ties. If Katniss ever wanted to find comfort again, she knew she had to return to Peeta for the long term.
Katniss blamed Gale for the death of Prim. She would never be able to look at him again without thinking of his part in her death. Gale was the best friend he could have been to her at that moment. He knew her so perfectly to understand this, he knew his chance with her had passed.
When Gale is most in pain is when Katniss kisses him, and this is true again as we see her answer Gale's pain with a kiss. She wants to give Gale what he wants, but she can't yet completely commit to him, as she must think of her family and Peeta and being the Mockingjay for the revolution.
Gale constantly does not understand katniss' trauma, and puts his feelings above hers every time. She is left traumatized from being in the hunger games and killing other kids, and all he cares about is her relationship with peeta, which was an act of self perseverance on her part.
Katniss comes close to crying, something she knows she mustn't do because it would indicate weakness to the other tributes and make her look vulnerable; thankfully, Haymitch distracts the crowd and the cameras by stumbling off stage.
Hunger Games: Why Katniss Ends Up With Peeta, Not Gale
Who killed Prim Hunger?
Before the Capitol battle, Gale had explained to Katniss his series of bombs designed to feed off human compassion: a small bomb would go off, and then when medical aid rushed in, a second bomb would go off, killing those people as well. Incidentally, it's this exact type of bomb that took Prim's life.
Answer and Explanation: Prim is killed by a bomb at the very end of the battle. Alma Coin sees an opportunity to turn the Capitol troops against Snow, and she decides the resulting loss of life from her plan is a worthwhile price to pay.
Although she will never know for sure, Katniss does recognize that she cannot be with Gale. She will never be able to forgive him for his idea — the parachute bombs — that killed Prim.
Katniss didn't really have the time to consider romance when she was worried about survival. When Peeta and Gale both made their feelings clear, Katniss wasn't entirely receptive despite caring for them both. In the end, her feelings for Peeta and Gale diverged, with Peeta ultimately winning her heart.
When Katniss comes home to District 12, Gale immediately confesses his love for Katniss, and she realizes she might have feelings for him, too — but she can't explore them, because she has to continue her fake relationship with Peeta or else her entire family, including “cousin Gale,” will be killed.
Gale is jealous of Peeta and the relationship he has with Katniss, and he wants Katniss to decide between them, though he doesn't press Katniss during her recovery in District 13. Gale is an excellent hunter and excels at setting snares and traps.
On the other hand, while Gale also wants to create a better world, he tends to be more violent. Gale is resentful and believes the ends justify the means. While Gale's strength was necessary to win the war against the Capitol, Peeta's peaceful personality is ultimately what Katniss needed in a person.
At the end of Mockingjay, Gale relocates to District 2 and begins working in the district's government. He helps train replacements for the Capitol's Peacekeepers.
She later realizes, after a conversation with the imprisoned President Snow, that President Alma Coin sent Prim to her death (which was caused by a hovercraft by the rebels) both to sway the Capitol citizens to Coin's side by making them think Snow was bombing the children, and to swing Katniss to her side through the ...
Gale does not marry anyone in The Hunger Games. He and Katniss talk about running away together and starting a new life in the wilderness, but they never officially marry.
He Didn't Save Peeta's Family But some people believe Gale may have had more malicious reasons for not helping them. However, Peeta's family wasn't great. His parents were abusive, or at least distant. It would have been interesting to see what would have happened had his family survived, but no one missed them much.
He has betrayed her and is betraying all of District 12 by buddying up with the Careers, whom she calls the "Capitol's lapdogs." She decides that if the Careers don't kill him, she'd be more than happy to. Then, she wonders why Peeta hasn't told them about her bow and arrow skills yet.
After Prim's death, Gale leaves voluntarily because neither of them can avoid the matter of Prim's death having been caused by Gale's invention, with Katniss letting him go without a word. Katniss subsequently grows back together with Peeta, whom she finds she loves again now that he is recovered from his hijacking.
Katniss speculates that Coin deliberately sent Prim to die in the Capitol bombing in order to fully gain her trust, but it's never outright confirmed or denied.
It's only implied that they get it on via snuggling and other affectionate acts in close quarters — but if you have read the book, they really imply that they took their relationship to the next level.
Prim was among the medics who arrived to treat the victims. Unfortunately, a second batch of bombs were set off, with Prim being killed in the explosions.
Even if Gale didn't intend to murder Prim specifically, he certainly intended to murder somebody. The two-phase bombs that he and Beetee invented were very clearly made with the intent of targeting medics and other civilians trying to save those wounded during the first phase of bombing.
