Boars i can understand, boars are just boars, the only tameness with them is that they decide not to bite you cause you feed em, lox's don't exist, so 'we' can say what ever we want about em.

Wolves are pack animals and they will defend their territory and their pack, from other wolf packs. A wolf not attacking another wolf makes absolutely no sense what so ever and no one would think 'wolves shouldn't defend me from other wolves'
It's just an 'oh ♥♥♥♥' moment.

regarding taming maybe put a 'tamed wolf will not attack another being tamed wolf' or what ever, i choose a wolf defending me over a wolf licking it's balls as i get mauled to death :D

I'd say.. It wasn't put in as a game mechanic but as an easy way out and i think valheim should be beyond that now.

i am so down with special taming pens for wolves, have them fight if 2 are in a pen and one tames.. atm they're a novelty, give me a good reason to breed em, have em defend me in the mountain, make it a fan fare, they're made for the mountain and they fail at it. :/