I did the same; many attempts to get a band together, many false starts. I gave up completely and didn't touch an instrument for a few years. I drifted back to playing guitar after a friend persuaded me to jam, but that didn't go anywhere particularly (although we wrote some great songs and had lots of fun playing them), and when it was obvious that it wasn't going to be a long term thing I had a word with myself and thought: what exactly do I want from playing music? It turned out that fame, fast cars and success wasn't what I wanted at all - I just wanted to have fun with my friends, so I did what I thought I'd never do, and formed a covers band at the age of 43, moving to bass as I did so. I've never enjoyed playing as much as I am now.
Perhaps tossing it all in is what you need to do, I don't know. What I do know is that until I changed what wasn't working, I was in that endless cycle of starting bands and them slipping through my fingers until it was no fun.