It seems that the institution of marriage is the issue and not human relationship?
Tie in the fact that the average salary can't support the 'traditional' lifestyle, and the desire for 'traditional' dating expectations. And now you have men checking out for one of many reasons, for example: not making enough with the right type of career.
And personally I see an unsustainable desire in women my age to travel. So instead of saving for the outcomes they might want (marriage and kide), an expectation that the man will provide the necessary support.