I don’t understand that either - not to say I’d discredit the fear, just that I don’t get how it happens as I’m dumb. But there are a lot of difficult to explain phobias, for example I get very afraid if I enter a room or corridor with lots of doors, all looking very much the same with basically no distinction between them. Probably some horror flick I saw way too young reference.

But space (distance between things) I don’t get my head wrapped around; I can easily imagine being between in 2 distant objects is scary, or trapped on one with no way out during imminent catastrophe, be it space or sea or even on land like in the middle of desert. But not when you are on cozy, mostly safe location without need to move to the other.