What are we grieving? We are grieving the loss of connection with that person (soul + body). It is very fair and basic that we feel extremely pained in such situations. As we understand the nature of the soul, body and the higher thatvam, God – the pain will translate into conducting yourself better with the situation and also spending time in the right way until you are in the current body.
Whatever one is experiencing – the grief, the sadness or any emotion is the result of connecting yourself with the current body. State of body changes constantly, therefore all the emotions you are experiencing are also constantly changing and ultimately perishable. Accept this and move forward. When you connect yourself with God, then the Imperishable state of Joy begins actualisation. Use the body to conduct yourself, and not make it the only companion! God remains your unchangeable ultimate companion, Relish the journey with Him!