I believe this sentence should be removed, at least if I understand it correctly. Based on my Russian knowledge (native speaker), this sentence would mean something like "You came without a friend?" when you're coming to a party or something. However, in English "Are you without a friend?" means "Do you have no friends?". Translating this sentence directly is therefore misleading. Is the Ukrainian meaning the same as the Russian?
This is a very weird sentence in Ukrainian too. It needs more context, more words to explain what's going on. E.g. "Ти в кіно без друга?" -> Are you in the cinema without your/the/a friend?
Otherwise, it doesn't mean "do you have no friends" and is very confusing out of context...
I would remove it :)
In English, "without a friend", "without any friends", and "without friends" are generally interchangeable. I don't see why one of these should be accepted and not the other versions, unless there is something in the Ukrainian version that specifically focuses on the number one.
Well, in this particular case, you typing "without any friends" may be because you thought "друга" is a Genitive plural form, while actually it's Genitive singular. So we can't freely interchange these.
Also, "without a friend" and "without friends" can mean different things. Без друга can also mean without your/the friend.