"I've been practically ripping your clothes off every time there's been a camera for the last year!" Catching Fire, page 216.
When they are in public during the Victory Tour, they are a unit. They are close – so close that there are very few instances that they are not together (the audience doesn't like them apart as much as they love them together, especially not her) – and they are always touching. They embrace, hold hands, wrap an arm around each other, a hand would rest on the other's knee, and they kiss. They squeeze in a kiss whenever they can. They're supposed to be in love, aren't they? They must keep up the act.
Out of the two, Katniss enjoys the kissing the most – even though she doesn't want to and wouldn't ever admit to enjoying any bit of it. Her body responds to him, but her mind is often focused on other things. Peeta wonders if she's ever wished that Gale were in his place.
But that just proves how much he doesn't know her. Katniss would never wish for Gale to be in his place. She would never want Gale to be in this situation, and she would never want their relationship to be built with lies.
For his part, Peeta likes the kisses, and he knows it. But he doesn't take advantage of the situation, because he wants it to be real. So what he does is pull her closer, revelling in the heat of her body, of her fire. He knows that he could never allow the Capitol to extinguish that fire.
Katniss is less invested in their relationship – or, rather, she doesn't feel the same about them as he does – therefore, she has no problem with taking advantage of the situation. She wants her family safe and sound, after all, and the only way to do that is by convincing the audience and Snow that their relationship is real. So she pulls Peeta to her and allows her hands to travel where they want.
All without being too inappropriate. She can feel Effie Trinket's stare burning a hole into the back of her head if they near going too far. Katniss wonders what the escort thinks happens at night, when Peeta slips into her room. She decides that she doesn't care one bit about what Effie thinks of them (of her), and gives the audience a good show.
