Nations were immortal. Even through bad times no one ever heard of a nation dying. Sure the greats had faded away once they had become absolute, but they weren't dead and gone, there were even tales of them visiting their descendants.
The relationship had a rough start, Prussia always mistook him for America, and every action was brash and without thought, unlike Canada who was reserved for planning. But small things drew them closer over time. When Kumajaro had attacked Gilbird thinking the little chick would be a tasty snack was the first time they really talked. Apologies spewed from Canada that usually his pet was far more behaved than that. No hard feelings were made and they went out for an apology drink on Canada. It was shortly learned that the Germanic nation as well as the Canadian, while having an affinity to dark brews were both unfortunately light weights.
Names were exchanged instead of titles, the Canadian being called Matthew by his friends and the Prussian who went by Gilbert when he was comfortable. The world conferences were the only time the two talked normally, sitting next to each other during the conference. The nations ignored them both for different reasons so what was the use of paying attention, for the first time Canada hadn't been a stuck up goody two shoes.
Nations could get sick, so when Matthew came down with the flu, Gilbert had wasted no time to nurse him back to health with soups and liquids. If Matthews family wouldn't do it, he would, even if his cooking wasn't the best it didn't compare to how bad England's would have been. (Besides, it kept Prussia well stocked with maple syrup).
1947 something changed. It was gradual, and if Canada hadn't been talking with him for a while, he never would have noticed. By 1952, Matthew was worried sick, but he spent his time ignoring duties to spend time with Gilbert. Maybe it was the mutual crush as Gilbert shut up Matthews worrying with a kiss.
They started doing sports together, friendly competitions of ice hockey that led to hot chocolate cuddles, but by the 70's, sports had to end when Gilbert kept falling and breaking bones that he shouldn't be able too. When his immune system started failing, Canada started begging for help.
Germany didn't remember.
France recognized the name, but still couldn't place the face.
Gilbert wasn't as active as he used to be, but they still went to the conferences. Canada wished that Prussia would stay home to rest, but the sickly albino was stubborn and acted without thought. No one paid attention to either of them as always, even when he asked people to say hello to Gilbert. For once, Canada had more attention than someone, and it killed him.
America did have the decency to realize trades with Canada had been down, so he went to check on his brother. Matthew was visiting someone in the hospital, connected to life support. He vaguely recognized the face and figured it was a politician.
Nations fade, but no one said that they would be forgotten too. Unfortunately you can't die from a broken heart but you can sure as hell try.