Analyze your relationship lately. Surely you often quarreled and abused, you have used any excuse to take offense to it or make snide, derogatory remark. As a result, neither you nor he did not feel the need to each other and loved ones.
In fact, two people who are not related by blood, initially connects with each other mutual attraction and passion, and then - the feeling of love. It is in need of care for each other, to ensure mutual physical and emotional comfort. When mutual existence becomes a torment, there is doubt that you are loved and needed his partner. This is enough to man felt unnecessary and just walked away, freeing the second of its encumbering presence.
Look inside yourself - whether you like it. If so, try to understand, in spite of all their grievances, what were your mistakes. If your constant carping were motivated by a desire to make it better, then admit that this is not the way in which it is possible to succeed. Reconsider their behavior, try to take him to objectively look at myself through his eyes, and much will become clear.
If he went into a fit of emotion, so nothing has been lost - you and your love to him indifferent. So there is hope that when he sees that you have reviewed their mistakes and understand them, he will believe that you really love it and can return.
The second reason that was a man, may be the realization of the fact that your feelings are outdated and there is no love, there is a habit and emptiness inside. In this case, his departure will not be accompanied by emotional outburst. Most likely, this happens quite casually and calmly.
What, take it bravely, Humble and try to understand where even extinguished embers of past feelings, will not have the fire. Take it as an inevitability, experiencing and make conclusions for themselves that will help you avoid the mistakes made by the new meeting, which, of course, occur.