The fuel lines are hard to remove, depending on the method used, and how you push the connection together along with using a tool. But the actual tool matters also, not every different type of line tool is perfect or works every time on all connections.
I have several different line tools, the plastic individual type were my first and I still like those the best. Those are a bit longer than most other types, and with gentle application, they work almost every time. But I have the cheap scissors kind, and two other aluminum line kits. I've also use high end tools from Mac and Snap-On.
How the tools are used is most important, go through that process very slowly and be sure the joint moves freely. The locking springs and clips inside the connection female side, they can bend or break. If the joint isn't coming apart with the proper method and tools, it's possible one or more of the metal clips or tabs is bent and will not release.
I had the big end of my tank line do that, it was that way the first time I tried to replace the pump. I got it off, but it took a thin screw driver and some serious prying. I knew it was messed up before I started, because the line itself was flopping/damaged back in the flexible section. I was very careful with it the entire time, and did get it apart. I had to drop the tank two other times, and the last time I had a spare line ready to replace the old one with.
You might have to get very rough with it soon, and if so replacing the line may be the only good solution. Go at it again slowly, they are not easy every time for anyone. Once damaged somehow, they will always be hell for the next person. Good luck,
