These two kings weren't just diplomatic buddies - they actually had a real friendship going on. They'd meet up regularly to talk about IMPORTANT ROYAL STUFF, like... well, who knows, but it's fun to imagine! Maybe they'd swap stories about their favorite palace decor or royal etiquette faux pas.
Anyway, King Carl XVI Gustaf said that Harald V's death felt deeply in Sweden, which is pretty cool. It just goes to show that even royals can have real emotions and actual friendships. I mean, who wouldn't want to be buddies with a king, right?