I think some intense emotional upsets can be like a fire. I have been through some terrible emotional anguish in my life and it was like fire.
It is only my opinion but I feel separation from God might be similar to the loss of a loved one, an intense burning anguish.
I think its helpful to talk about things that happen in this life. If separation from God is like a burning fire, then those who are separated from God in this life are experiencing it in this life.
I do agree that being separated from a loved one feels like hell. That's one of the reasons that heaven and hell cannot exist as a place where people who love one another are separated after death.