Each of those experiences helped me grow, and I think the situations are very similar to the ones I see friends in. I wan to tackle one of those items today and others in later posts.
Talk To Your Boss
I used to be like most people, afraid to let my boss know I was leaving. I came out of the restaurant business. If you told your boss you were looking, you were fired. A lot of professionals have that view, and it's somewhat justified, but less and less so.
There are certainly bosses out there that take an employee leaving as a sign of disloyalty or disrespect, or more likely, a sign the boss is a failure. For the people that have those views, only the last item is true. If you have a boss like this, then you can't tell them. In fact, if you have a boss like this, that's probably the reason you're leaving.
In that case, I recommend constantly looking. Keep blogging, updating your resume, networking, and looking. If your boss asks, just let them know you're providing a layer of security in case the company experiences a downtown and lays you off. It's plausible, true, and likely not acceptable, but since it's your life and career, I'd do that.
However for most of my employers, and fellow managers when I managed, having a conversation about leaving is an adult affair. We can mutually discuss the issues, and often we find there's nothing that can be fixed. Money is often limited, though if this is the only reason, sometimes a change can be made.
If I (or you) want more responsibility or different projects, then part of the issue certainly is communication. The employee needs to let the manager know, and I've been guilty of this. Sometimes there can be changes; sometimes there cannot. At least not in the short term. If the issue is that you aren't ready, then a manager should help you understand where you need to grow, help you find training, and make a plan.
If you have culture issues with the company, often that's that. I had a few people work for me in this place, and we worked together for an orderly transition. One to a new company, one to a new position in another group, and in a way that didn't disrupt my team or cause any poor feelings between anyone.
I think most of you will find that your employers are grown up and understand that many people won't work for the same company for 40 years. Many of your managers will look to move on at some point, and they understand your desire. Good managers will help you, poor ones will sulk, but few will actually actively sabotage or fight you.