Actually, you're missing my intention. I'm not saying you can weasel around it so it's not שקר. I'm saying what the תורה considers אמת isn't always what we would objectively say is so. Lying for שלום בית is מותר not because there's a temporary pass on שקר, but because as far as G-d is concerned the אמת in that situation is to preserve שלום בית.
I don't disagree with you, but i don't see the benefit on the other side of the scale in this case...i think you're missing the point, it's not that lying in the service of shalom bayit is not lying, and therefore אמת, rather, that there are 2 principles on the scales here, אמת and שלום, and the halakhic decision is that in this case (as in many others), שלום takes it. There are, of course, cases in which the opposite is true - for example, the חפץ חיים's descriptions of when it is not only permissible but sometimes obligatory to engage what in other cases would be considered
lashon hara, because there אמת is considered the more important principle...