And if there's a bunch of singles in a group, it could well be possible it's because they're a singles group, and they're there not to just hang out with each other, but to watch out for another.
Exactly. One of the reasons women group up like that is because it makes us less likely to be hassled by men. Most women don’t go to special events because they’re hoping men will flirt with them; they go because they’re interested in the event and/or want to enjoy themselves. There are few things more annoying than having to think of a way to politely tell a man to leave you alone. Hence, women go in groups of two or more to make those situations less likely.