Well, it has been stated by the author in an interview that the rings, insted of marriage, they were a symbol of them being soulmates while also being lucky charms. And also that the ring exchange scene was destined to happen.
Besides, for an ice skater, a lucky charm always seems to have an emotional significance. And they usually wear necklaces as lucky charms, while Yuuri chose a pair of gold rings. Of course he didn't buy them to propose, but they are still a meaningful pair of rings someone wouldn't buy just for his good ass friend..................sorry for ranting ( ̄∇ ̄")
Victor LITERALLY calls them engagement rings. Literally.
Like, different ways to read media I get. But denying what's explicitly stated is delusional.
(Also, authorial intent is just authorial intent. What's there is what's there.)
I do ship yuri and victor more than Yurio and yuri but yuri is not cheating on victor in any way, those rings SO FAR in the anime have been good luck rings, like really good friend rings. So far at least, probably later in the anime victor and yuri will see the rings as something more romantic or maybe they already do but that hasn't been stated in words at least in the anime. Chill with the yuri's cheating. I'm not trying to offend anyone just want to put my two cents in.(づ ̄ ³ ̄)づ