I have ED-E and Boone and neither of them can die, whenever they should be dead it just labels them as unconcious. Boone will get back up but ED-E will only come back after going through a load door.

Is this a glitch or should this be happening? (I doubt it as it renders companions useless, and kinda takes away alot of fun as i no longer have to care about them)

turn on hardcoe mode.

It should be happening provided you are not in hardcoe mode.

They die in hardcoe mode. Sadly, I've lost Rex and Boone.

Yeah, I lost ED-E in my game.
R.I.P you floating spherical jukebox you.

Although I did wonder for a few minutes why I couldn't just repair ED-E

i lost veronica while taking a shortcut to an area for her quest, because all i'd seen in the area were weak scorpions and i didn't want to backtrack and find the road again. i didn't see the giant radscorpion until it was too late.

i felt really bad afterward ;_;

Companions being invincible in normal mode was one of the main reasons I started in hardcoe mode... seemed lame to me they couldn't die.