Junto?
“Sola?” Carlitos asked me a bit curiously when I showed up one night at the practica without the accompany of my friend. My dear kindhearted friend took me to the practica at Sunderland first time, (and a couple of times after) and introduced me to Carlos and Rosa, and other acquaintances. The very same night, people inquired if I was the Novio. 
Another night, I went to Nino Bien with a good friend who is a professional. She got us a very nice table by the piso, front row. We were having a good time, chatting, people watching and commenting. We danced our first dance together…
The moment I met with a portena later, whom I got acquainted with in the milongas, for a tanda. Her first question for me was ” is that your girlfriend?” My friend told me later that at least twice she was asked if I was the new boyfriend.
Isn’t it an outdated mentality that tango is only for hooking up with someone? Can man and woman just be good friends, sharing a bottle of champagne or beer or wine together, having a tanda or two? Why must some people assume that because two show up together at a milonga, they are, by default, lovers?
Apparently, in some minds, tango is just a means to get some… 
Oh, no, I don’t agree: it’s just the codigos in Buenos Aires. If a man and a woman are only friends and not a couple, they don’t go to the milonga together and sit together. Of course this isn’t true in other countries and it doesn’t have anything to do with the tango per se. It’s just another unwritten rule of the milongas here. (The “solo?” question at the door usually has to do with where you wish to be seated, not your romantic status.)
That’s just one of the about 40 codigos of the traditional milonga!!
Will miss you; come back sooooonnnn!!!!
You may as well ask “Why is the world round?” Things are just the way they are.
Factor in also that BsAs milongas can be somewhat conservative and old fashioned. And that strangers will want to know whether you are “taken” or not.
Often I find these questions rather flattering. If I go to a milonga with someone who is a professional , my usual reaction is : “If only… “
Well, while in the more younger crowd milongas/practica, like villa malcom, milonga 10, it seems nobody cares whom you come in or sit with.
People want to know your status. The young ones and those who haven’t been going to the milongas for years have no qualms about asking the question and hoping to get a straight answer. Women want to know if you will be available for tandas. If you are with your sweetheart or dance partner, it is less likely they will get to dance with you. It seems obvious that is you enter the milonga with someone, you are there together and intend to dance only with each other. Those who know the professional you are accompanying will assume you have paid for a private class with her; that’ the reason she is with you. Actions speak louder than words.
You should have realized on previous visits that there are usually three sections in a milonga: one for “solos” (single men), one for “solas” (single women), and one for couples. They want to know this information in order to seat you in the salon. If you are “solo” you will be seated at a table with another man. If you arrive with a woman, you will be seated in the couples’ seating which is usually out of range for the cabeceo since neither will be dancing with others.
I am interested in those 40 codigos of the milonga that Cherie mentions.
When I go to milonga, I would tell the host “solo” to have a seat at the men’ side. When Carlitos asked me “sola?” when I showed up at the practica alone, he was surprised that I came in without my friend. As I noticed, that in traditional milongas, people seemed to pay more attention to with whom one comes to a milonga and sit together. In the newer milongas, young people seem to care less.
In terms of me sitting with a well known professional, anyone who has seen me dancing on the floor, in traditional milonga or new milonga, would not assume that I need to pay anyone to dance with me.
And I have been very selective about with whom I invited to dance. A lot of times, I had to look away in order to avoid cabeceo. I would be modest if I say that I am a good tanguero. 