"And remember, I am with you always, to the end of the age." (somewhere in Matthew?)
As long as you remember them--and what and who you were in their physical presence--they are there with you. Not the same, surely, but comforting nonetheless, at least to me.
I was emotionally and physically shattered when my youngest brother (who suffered from a devastating mental illness) passed away suddenly at age 55. That was over 20 years ago, and there are days when it hurts as if it happened yesterday. He loved to laugh, and to this day, I begin every day with two things: laughter and music (preferably from the throat of a bird). May it always be so.
DO NOT STAND AT MY GRAVE AND WEEP (Mary Elizabeth Frye)
Do not stand at my grave and weep
I am not there; I do not sleep.
I am a thousand winds that blow,
I am the diamond glints on snow,
I am the sun on ripened grain,
I am the gentle autumn rain.
When you awaken in the morning's hush
I am the swift uplifting rush
Of quiet birds in circled flight.
I am the soft stars that shine at night.
Do not stand at my grave and cry,
I am not there; I did not die.