Okay so when I went to Cottonwood Cove to the main quest boone basically says that if you take him down there hes going to start shooting. So I hit the third speech option to telling him to leave. But now hes neither at the Luck 38 nor Novac. I am playing on hardcoe so i dont know if he died trying to get back to Novac or the 38(if that can happen). So does anyone know where he disappeared to this time? :facepalm:

Since you fired him (you no longer have his perk), he went back to Novac. The 1.2 patch fast-travels him there. He should be in his motel room or in Dinky on his shift after 9pm.

They still don't fast travel, when fired, for me. If you saw him actually walking away from you, then....well...either he's taking longer to return home than he should, he's in his motel room/Dinky, he's dead, or he's glitched out somewhere. It's possible if you just travel around for a while, let some days pass, he'll show up in his home location after a while.