In my opinion, if you can't be arsed to write up a proper treaty (which can take like what, 5-10 mins? Not even that if you use a pre made draft, edit it to your liking, and bam, treaty), then you aren't actually arsed about the friendship. Hell you don't need a treaty to say "I love you."
VE did this with Athens in the WWE, they do something similar here, of course you can see why I am thinking this way.