I do pub trivia every week with a group of friends. We've been doing this for five years, and know each other well. Two weeks ago, one of my friends "Jim" unexpectedly brought along a woman "Janet" who we'd never seen before. He introduced her to the rest of us by saying "Everyone, this is Janet. Janet, this is [runs through our names]." Jim and Janet sat next to each other, but seemed to interact just as friends (no touching, no pet names, or anything that could be construed as couple-y). They also both paid for their own drinks.
Last week, Janet didn't come to trivia. But last night, Jim bought her along again. They sat next to each other again, but quite close together. A few times, Janet rested her arm along the top of Jim's chair (without actually touching Jim). Jim also paid for her drink.
At one stage, when Janet visited the bathrooms, another friend "Ricky" asked Jim, "So, ah, Jim. Is Janet a Special Friend?"
Jim replied rather brusquely "She's my GIRL-friend." The tone of his voice indicated that he considered Ricky's question to be a silly one, and that Ricky should have used his common sense and got the clue that he and Janet were in fact, an item. I should add that after Janet returned, Jim was more demonstrative with her, holding her hand, etc.
In the past, I've also experienced - with a different social group - several instances where two friends (who had previously never shown any romantic interest whatsoever in each other) suddenly turn up to an event or party holding hands, or with their arms around each other's waists, or displaying other couple-y behaviour. When that has occurred, I've privately assumed "Oh, Bob and Mary must be dating now. Wonder when they started going out?" Nine times out of ten, I've been correct, but once or twice, it transpired that the people in question had simply developed an extremely flirtatious friendship, and still classified themselves as single.
Basically, sometimes it can be confusing as to whether people are in a relationship or not if they don't actually say anything! And sometimes I do need to know the relationship status so I can adjust my own actions accordingly. (For example, in Jim's case, I now know not to offer to set him up with my friend Kathy from work, as I was going to. Or we now know to leave two spare seats together so that Jim and Janet can sit next to each other at trivia, etc).
My questions are:
1) If a friend brings someone new to an event, who could be a potential date, is it rude to ask them whether they're actually dating that person?
2) If two friends show up suddenly displaying couple-y behaviour, should you assume they're a couple and treat them accordingly like a social unit, etc?
3) On the flipside, does etiquette dictate that you should let your friends know in advance if your dating someone. Or is it acceptable to show up to an event holding your new partner's hand, and assume that all your friends will take the hint and understand that you're an item?