You will probably need some assistance of some heat like mentioned before but before you do, soak the assembly in a 50/50 mixture of transmission fluid and acetone. Acetone can be bought at a hardware store in the paint section. This mixture works better than any commercially available penetrating fluids. Also, some extra leverage may be needed from the wrenches you are using.
Sometimes the fuel line rusts to the tubing nut, and then the flare gets frozen to the housing, so carefully drilling out the fuel line with the correct size drill [same size of fuel line] may help free things up a little too [Don't drill to far or you will run into the housing].
To prevent this in the future, I use chassis grease upon reassembly on the fuel line and the threads, don't use Teflon tape, it may get sucked into the needle/seat.
Maybe some day I will post a picture of my Q-jet, which I use a nylon fuel line with a quick release fitting-no tools needed, just pinch a plastic retainer and pull it off!
With patience and a little luck, it may come out without damaging the housing.