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In this situation I think the duty of care lies with you. You should check with the other owner before letting your dog approach theirs. This comes with a big warning, pretty much all dogs will fight and there's always a first time! The other problem is that many owners are in denial of their dogs temperament.
This makes me sound heartless, I'm not and am sorry that your dog got bitten, but I am a realist.
Tbh I appreciate the other point of view! I've been working on the assumption that if someone is playing fetch with a dog in an open field near another person playing fetch with a dog, their dog is okay to be approached by another, and I guess that's not quite enough.