Learning guitar is not hard.
It’s fun 
It’s only hard if you set yourself goals that you struggle with.
I’d be hard pushed to play a single song from start to finish from memory, and I doubt I’ll ever learn 20 (although it’s something I’m working on at the moment ).
I don’t want to rehash our differing opinions and hope you don’t mind if I repost a link that deals with some of the issues being discussed here. It contains some interesting thoughts.
I don’t quite understand your motivation though @Svenssen. You say you started again for various reasons and you are frustrated at not improving your skills. Do you not enjoy playing? There will always be higher levels you can or will not attain, no matter how good you become. If you’re not enjoying the process, you might want to rethink the whole endeavour.
I hope you find your path