Many Chinese girls are highly insecure and are prone to cheating. The Chinese word for cheating is pitui (劈腿 – pronounced pi-tway), which literally means to do the splits. Before marriage, a man’s Chinese girlfriend will always be on the lookout for a better boyfriend. If she finds a guy who appears better than her boyfriend (e.g. bigger house, better job), she will date him behind her boyfriend’s back, and only after everything is good with the new guy will she leave her bf. The reason for this is simple: A Chinese girl is defined by her marriage. If she is not married, then she is nothing. This is why that even if she is unsatisified with her current boyfriend, she will still stay with him for fear that she won’t find a better one. It’s like insurance.
I have not once seen even one case where a Chinese girlfriend has left her boyfriend cold turkey. Everytime she has gone straight into the arms of a new guy. Before these girls are actually married, they consider themselves to be fair game. Therefore, if you notice your Chinese girlfriend becoming “good friends” with a guy who is richer and possibly more handsome than you, you’d better have a backup plan.
Of course not every girl is like this, but the behaviour I have described is much more socially acceptable and common amongst woman in China than in western countries. In much of Asia marriage is more for practical purposes rather than for love, so it makes sense for a girl to “shop around” before she makes her final decision.