People don't stay forever but they are like sunset that makes our life beautiful and then vanish when it's their time. It sound sad but I think looking the idea of how they give something to our life can also put a smile to our faces. The memories we thought painful to recall because it reminds us about those people we loss turn into a happy film reel inside our head.
Losing someone doesn't mean that's the end, it only means that we have a different journey ahead. We will meet new people, they will come and go, some of them stay a little longer to the point that they were able to grab a small piece of your life. But then, at the end of the day they cannot stay forever. Like I always said, we only have a lifetime in this world and lifetime cannot hold forever.