This is going to sound ridiculous, but thinking about time as a 4th dimension helped me. The past never disappears from our universe, it's just the previous page of the book we're reading, and always there just a short distance away along the axis.

This helped me reframe the loss from "they're gone forever" to "they're alive, in the past".

It's now an inaccessible location to you, but the past exists in no less of a real way than the present moment.

And while that's not the page we're on anymore, that ink never fades. You shared those pages with them.

And if it occurs to you to think this way before they're gone, then I hope it also encourages you to fill those pages with the happiest times together that you still can.