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CMV: The Red Wedding was Justified

Spoilers ahoy. Be warned. Book and show.

The war was already over. Robb Stark had no chance of winning the war as soon Moat Cailan was captured. His supply lines were gone, his army was going to be forced to forage, and was going to starve to death. That doesn't even count the fact Lannister-Tyrell forces would outnumber. Some people claim he never lost a battle, does not mean he is a good strategist, just that Tywin decided to bleed Robb out of the war. And most of the victories Robb has were with him outnumbering his opponents. Not to mention the fact Robb had Winterfell for like a year, before it burned to the ground (don't give it someone else fault for this, it's his home he should be able to defend it or find people who can).
Robb Stark was a terrible leader. He failed to gain any allies. He couldn't get support for Stannis, Renly or Balon. Why because he wanted to be King in the North. Eddard, the person he fighting this war to avenge, didn't even want that, he backed Stannis. He willing gives over the only hostage he has that might detter Ironborn aggression. Then he honor kills Lord Karstark losing half his army. 

Robb Stark was not honorable in the slightest. Remember when I mentioned Moat Cailan? The second his home land was under attack, Robb should have sued for peace with Lannisters (or at least try to make peace with Stannis), and gone back up North to rout the Ironborn. For all his do the honourable thing talk, he doesn't defend his subjects well. Not to mention he uproots the entire population of the North right before winter. So now not only is population being pillaged, they are going to starve in the Winter, even if Robb wins, you think he'd know Winter is coming given that is his family's words. He also has a bad case of double standards. His mother removes the most critical asset Robb had in the war, and he essentially slaps her on the wrist for it. Additionally, his marriage. Book or show, his marriage shows a complete double standard to him and his men. Robb has his wife with him, while on this journey and battle, none of his common soldiers get that, they are all forced to be alone.  

So given the facts, you are in a losing war, you leader is incompetent and unhonorable, who wouldn't betray him? The leader was not performing the needs of the people so, much like Eddard did, Roose decided to remove a mad king. And thank the gods for it. Now, there is a hope that the North will be free from the Ironborn raiders, and might be able to feed itself in the coming winter.

Edit1: formatting

Edit 2: Hey guys this has been a lot of fun. I believe my view has been changed at least with regards to the book version of the events. Ramsay in the show is psychopath, but his damage is actually very small, he doesn't really salughter Northern en mass, and I would believe him better than Ironborn rule, and he is not the intended warden of the North. In the books however, he is and he is much more dangerous to Northerners, and the intended heir. As far as Guest Rite violating, I just don't really see the issue, yes long term consequence, honour holds the kingdoms together, but there are plenty of instances of unhonourable behavior not being punished in the real world and in Westeros (I think one of the Targaryens fend their sister to a dragon and violated the guest rite, and the black dinner it was bassed on was quite successful). If your liege is going to bring your kingdom to ruin you pull a Jaime Lannister and end them. I think you forgo caring about what other people think of you when you put a flayed man on your banners.   The unanswered questions are what is the state of the North during Winter, and will their be starvation there or not and how much. Also it is hard to know what the effects of the Stark armies movements are on the countryside. While Robb probably would not condone pillaging and rape, it is hard to know how effective he is at stopping it. I still believe Robb Stark blunder his way into losing the war, how many victories he got it didn't matter, he refused to have a strategic focus, and while he might be tactically brilliant, strategy wins wars. Thank you all for the responses, now lets all sing a round of the Rains of Castamere.
gpt
The issue with the Red Wedding wasn't that Robb was betrayed or assassinated - both are pretty common in Westeros (e.g., basically anyone who ends up on the Iron Throne, or Hand to the King, is betrayed and killed). No biggie.

What makes the Red Wedding (which is separate from the broader idea of assassinating Robb, which is fine) *unjustified* is that it violates the guest rites at a wedding feast, which is basically an unheard-of transgression. *That* is what makes it so shocking (both to reader/viewers and to the people of Westeros): it's the line that you just don't cross, because it's the moment at which you acknowledge that your word of honor cannot be trusted, and your enemies can never find accord with you.

I don't think Robb would have been a particularly great king (though he was young, and might have grown into it in time), and there's nothing wrong with the Tywin Lannister arranging to have him betrayed and killed. Happens all the time. But the *way* in which Lannister arranged his assassination was a miscalculated overreach, a move of desperation that largely set in motion Joffrey's parallel assassination at *his* own wedding and, indirectly, Tywin's own death.

Oops.