I've had some interesting conversations with a couple of people over the last few months about leaving their respective martial arts to try something new. They felt that the training they were getting didn't offer them what they wanted. In some cases, they felt that the school they were at was treating them unfairly. In every case, there was a sense (sometimes stronger than others) that by leaving, they were somehow betraying their teachers and fellow students.
One of them phrased it this way:
I have all these fears about leaving them - they are
my friends and practically family after all, and it's not as if I can
simply take it back should I change my mind.
This is not an uncommon message in the martial arts, but it should be. Because it is beyond disturbing--it is wrong.
This is not medieval China. You are a paying student, not a house slave. You are under no obligation to continue training in an environment that no longer suits your needs. If you want to leave, you leave.
And if you can't "take it back" then that is even more indicative that something is wrong.
[I am making the assumption here, for the record, that you leave politely. If you walk into the school, take a giant dump (literally) on the mats, make some unkind remarks about the questionable parentage of the head instructor, and spit on every student before you leave, you should probably expect that bridge to be burned. Rob Redmond has an excellent article on how to leave a school properly.]
You should be able to walk away from a school any time you need to, and come back without questions being asked. If your fellow students and teachers really are like family, they ought to support you.
A personal example: when I was in undergrad, I spent a few years studying Uechi-Ryu karate. After I graduated, I drifted away from Uechi in favor of studying other arts, most notably Muay Thai. Despite not having studied the art in over a decade, I'm still good friends with people that I met in that art. Several of my former training partners were at my wedding. One signed my ketubah. I've had dinner with my Sensei. Not one of them has ever given me more than friendly kidding about my decision to leave. My Sensei's mentioned that he would have liked to see me earn my black belt, but it's never presented in a guilt inducing sort of way. We've all worked out a few times, and I have no doubt that if I sought out my Sensei and told him I wanted to take up Uechi again, he'd welcome me back with open arms.
Which is how it should be.
If you can't walk away from your school and come back safely, then you need to walk away and not come back at all.
Change and Quitting
Know When To Walk Away
When It's Time to Quit
Karate Lessons Give Child Self-Confidence to Quit Karate