I have left bands or taken a haitis*, always on good terms with the other members, for various reasons: different musical goals, different professional goals, health reasons, a better opportunity presents itself...

I've found that if I explain my reasons for leaving clearly, that it can be done quite easily. If you have an interest in playing, an opportunity will present itself.

I still get together and jam with members of groups I have left and with people who have left groups that I stayed in.

*Is that how you spell it? You know what I mean.