First thing is melee range, which is not zero, which usually resolves that, I think it's 5'+weapon length in FRP. . .so with 4' sword, within 9' you're in melee range.
Next, exiting that area is attempting to break off combat, so if the orc w sword enters 9', then to back off you need to disengage to avoid being attacked.
last, you can move and attack if you execute a charge, which is often the best way to force combat on someone, but risky due to DB penalties.