And we never understand it and think that those who come in our life remain part of our life which is an impossible thing as one who is born has to die. :)
Yes. All that appear in your life are co travelers but will not stay with you for ever. This reminds me of the song- Jeevan ke safar men raahi milate han bicchar jane ko de jate hen yaden tanhai men tarpane ko ( we get in our life co travelers only to part and pain us for rest of life journey).