So, uh, if they aren't aware fighting is an option then would you mind telling me what WiH is about? 
Oh, they'll fight. But it'll be like Hannibal in the Punic wars. No matter how many times they are victorious on the battlefield they will never make the final push. They don't have the mindset or the capablity to truly go for the kill; it's not in their makeup. The UEF
might be good defenders, but wars are not won by defensive action.
Even without the desire for war, the will to live will be enough when in combination with their heavier emphasis on smaller ships when pitted against Shivans.
Whether 'tis nobler in the mind to suffer the slings and arrows of outrageous fortune, or take up arms against a sea of troubles, and by opposing
end them. Defensive warfare against the Shivans is a lost cause.
And if things got really desperate, they could always blow up the Sol gate. Of course, that's if it hadn't already stabilized the node, as the Knossos device in Gamma Draconis had. But that had 8,000 years to do so.
Somebody is forgetting their basic FS history. The Knossos stablized the node in the short period after its actual activation. Weeks or perhaps a month at most.
All of that aside, the fact that by the time WiH begins the GTVA-UEF war is 18 months old proves that they've had the will and ability to hold out against the GTVA. So there's really no base for saying that they're unwilling or unable to use force. If that were the case they would have surrendered or, at the very least passively resisted a la Ghandi. The existence of the UEF's navy is also a contradiction to that in and of itself. Normally docile animals become ferocious when cornered, and space-hippies are evidently no different. 
On the contrary. No modern state survives without some kind of armed force. The time period is not terribly relevant; we have no idea how the war has played out, what kind of forces the GTVA has actually commited to it, or how quickly the war is being prosecuted (though prose evidence suggests the GTVA is not making a rush of things), so drawing conclusions based on time is an irrevelance. Similarly, I never said that they will not fight; simply that they will never be good at it and never be able to make the kind of "total war" effort needed to prosecute a major armed conflict.
There's also another element that you all seem to be forgetting - morale. Look at it from the GTVA's point of view. We're fighting humans again, and for the first time the GTVA is doing so without provocation. Hell, half the fleet from AoA defected on the spot. Any pilot with a sense of morality would be horribly demoralized by what he was doing. And as for the UEF, they're fighting to defend their home - and succeeding against impossible odds. I'd think that defending one's homeworld would give one a great deal of ferocity in doing so. And holding out against a technologically and numerically superior enemy has to be great for morale once in a while.
Objection, assumes facts not in evidence. Again we have no idea what kind of forces the GTVA has commited to the theater or at what pace the war is being played out. From what we actually know, it seems reasonable to assume the GTVA is, in fact, winning. They're simply conducting a slow, grinding campaign, seeking to inflict maximum casualities for minimal losses to break enemy morale. For all we know the UEF's morale is shot, the GTVA is running high, and the GTVA is winning the war with a single destroyer and three and a half corvettes.