The woman, 100% of the time.
It may seem like that to men who pay no attention at all and expect everything to happen favorably for him with no communication, sacrifice or compromise, no matter how much the woman is communicating, sacrificing or attempting to achieve compromise. It comes as a complete shock to such a man.
His response is often, "She's crazy." or "It came out of the blue." or "it was just sex. It didn't mean anything. Why is she dumping me and hurting me like this?"