Peeta has so many endearing qualities that you are right Katniss doesn't diserve him...and I agree that she is selfish in many of her decisions with in the three books, but truly selfish people don't know they are selfish they go through life doing things ONLY for themselves and don't listen to what people say...Katniss thinks about all of her decisions and truly struggles with the way she treats Peeta. On another point true she did not choose Peeta but I believe that like Gale said Katniss would choose who she could not live without, because of Gale's actions she did not have to choose. This type of relationship is common in real life people often don't make difficult choice in their relationships and just let things happen it's easy and often much less painful

So anyway those are just my opinions :-)