Leaving a relationship is not easy. How could you leave a relation that sustain for long years. I knew someone who on getting rich started to exploit me or others. But being elder person does it make sense to leave them in hostility. We somewhere k ew that once theybrealised their mistake they turn to us. But having a soft corner, say bye or making distant is not easy.
I think this is another issue. People think of everything they've put into the relationship and it makes it hard to leave. The idea of starting off somewhere else or with someone else from scratch can be daunting. But then, I'm of the opinion that as long as it's messing with your mental health, leaving shouldn't be an issue. Starting from scratch shouldn't be an issue either. This is very important!