How infuriating for her! It happens more than many people realise. Not to say that most women - on the canals particularly - aren't massively privileged in most ways (ethnicity, class, wealth, health etc), but it does grind your gears.
Sometimes yes, sometimes no. I don't think single sex space promotes discrimination and can, conversely, be a comfortable place to discuss ideas and feelings. If you wanted to explore that argument, you could argue that it's not possible for a group to discriminate against themselves or against a more privileged group. You'd need a lot of energy, time and commitment to explore that on here though
Tell you what, though, you'd be hard pressed to get me into most art galleries!