You feel alone and adrift; you mourn the absence of laughter, companionship and caring. You might long for the days when everything was easy and all you had to do was show up.
Losing your lover is even more traumatic, as it represents a fundamental change in the dynamics of your relationship. Suddenly, you are no longer first and foremost in their lives. They will have new priorities and interests that take precedence over yours.
No matter how much love you've shared, there's going to be a certain amount of hurt and pain after someone dies or leaves you. But eventually, you'll come to terms with what has happened and learn to live without them.