Breaking up suddenly... how to overcome?

My freind and his girlfreind were living together for over a year and were finalizing the prepration for their wedding when she travlled abroad and simply broke up with him because she did not feel like herself around him, no problem that is her reason, but he is devstated and he simply can not get over her for almost six months now, he quit his job and staying on the internet for days (not hours) and I feel helpless in trying to help him, what can I do?