It wouldn't be a love triangle without a third leg, and Gale is most definitely the third in this party.
Basically, he's everything you'd want in a boyfriend: strong, hunky, principled, and even into the same things as Katniss (i.e., sneaking out past the electrified fence and shooting things with a bow). What more do you want in a bestie with benefits and possible serious snuggle-dude?
Well, there's that whole televised death match that stands a very good chance of killing his girlfriend.
Nothing snuffs out romance more than that. Not to mention seeing your sweetie pretend to fall in love with another guy for the benefit of TV ratings. But there's more to it than that; while Gale may seem like the perfect guy, there are a couple of things beneath the surface that raise a red flag.
A Man on a Mission
For starters, there's something he loves more than Katniss.
The sweet kiss of political freedom is never far from his heart, and he's pretty convinced that sooner or later, the people are going to rise up and stick it to the Capitol. You can see that in the frank way he talks about the Hunger Games.
GALE: You root for your favorite, you cry when they get killed. It's sick.
GALE: No one watches and they don't have a game. It's as simple as that.
He's lucky that the sharp ears of the Capitol can't hear his revolutionary talk. That makes him a crusader, which is admirable. But crusaders always put their causes before others, and Gale seems very interested in his. Considering his more or less implied revolt against the Capitol, that doesn't speak too well for his lifespan either.
Driven But Dependable… Like a Chevy, Only Sexier
That said, Gale is still the most trustworthy person Katniss knows in District 12, and that gives him a few advantages. For example, she immediately looks to Gale to take care of her family when she goes: not her mother, but Gale:
KATNISS: Take care of them, Gale. Whatever you do, don't let them starve!
That's a pretty big level of trust, and it means that, even at her loneliest moments, Katniss still has someone watching her back and ready to lend a hand back home.
He's also helpful in giving Katniss a little optimism before the Games. Given that Katniss is generally a grim sort, it's the sort of thing she probably needs to hear.
KATNISS: There's 24 of us, Gale, and only one comes out.
GALE: Yeah, and it's gonna be you.
Also, Gale's principles, and the hating of The Man that comes with it, prompts him to give Katniss some useful (and lethal) advice before she gets dropped into the blender.
GALE: Get to a bow.
KATNISS: They may not have one...
GALE: They will if you show 'em how good you are. They just want a good show. That's all they want. If they don't have a bow, then you make one, okay? You know how to hunt.
GALE: It's no different, Katniss.
Killing animals, killing people—it's all the same, right? That's pretty hard-core advice, not only in terms of giving Katniss the eye of the tiger, but in reminding her that it's all on television, which carries rules that she can use to her advantage. They do, indeed, love a show. Fancy tricks with a bow—especially tricks that end with arrows sticking out of other people—can make a huge difference in attracting sponsors and staying alive.
We hardly see him after those first few scenes, but he's been behind the scenes, taking care, we assume, of things back home and anxiously watching Katniss's adventures on TV. As the train carrying the victors pulls into the station, it's a stunning moment. Katniss spies Gale in the waiting crowd. Peeta, who's just accompanied her though hell, is standing next to her.
The world of Gale and home must seem unreal to her at this point. Can she ever feel the same way about him? Of course, it's not his fault that he wasn't chosen by random lottery to slaughter 23 other people. We're left with the question: have the Games made everything else meaningless for Katniss? Can Gale ever be part of her life again? Should you ever love a revolutionary?