A civilised lesbian's conundrum with the concept of facebook wives reminded me of an immensely disappointing confusion I had learning German.
Basically I fancied this Austrian girl to bits. Took me a while to realise that, every time a female German speaker says "mein Freund" (as opposed to "ein Freund von mir"), she doesn't mean "my friend [male]". She means "my boyfriend". Quite annoyed when I clocked that one, I can tell you. These things tend to work both ways, though, and teaching English to Germans, I gradually discovered they would say "a friend from me" rather than just "my friend". This was when they were men talking about men they got on with. Girls talking about girls, it would always be "a girlfriend from me", or else "my girlfriend", in the baffling American finger-wagging sense.
This is a whole new set of distinctions to learn with each language: we don't distinguish the platonic word by gender, they don't distinguish the masculine or feminine word by whether or not they've snogged. And when Germans use English words, they tend to use them in rather German ways. So a German website "friendscout24", though it uses "friend", which would be an emphatically fully-clothed relationship in English, has obvious connotations of romance for Germans.
This stuff is weird. And I've not even thought about how it must go once you chuck in homosexual relationships. In fact, the entire language of boyfriends and girlfriends is euphemistic to the extreme. Firstly, it's more than just a boy or girl (or lady or gentleman, once you reach a certain age) that you're friends with. Then you've got 'relationship', which is also stupid. I've had a relationship with every student I've ever taught. I was their teacher and they were my student. 'Dating' is even worse, and 'sleeping with' and even 'shagging' are just as incomplete. So no wonder it's just as weird and confusing in other languages.