Please don’t ever tell someone that they need to get over their grief. Grief is something you get through and you never truly get over it.
Each person has their own journey through grief and telling them they are doing it wrong only adds guilt to the pain.
If you want to support a griever be available to listen. Understand that their pain may make you uncomfortable, especially if you are not okay with your own pain. But if you can sit there with them without giving advice or imposing expectations you will be doing God’s work.