Don’t be so hard on yourself and don’t take things personally.
You did your best to find a place to work that matched your belief system. After three conversations, you had a good feeling that you had found the right fit. But things change. At large and small organizations. You change, too. You learn things about yourself and discover other paths that look more promising. Companies do the same thing.
It could be the timing. It might be that you’re in the wrong position. It’s possible that it’s a combination of both. Regardless, don’t let it get you down. Building a career is about applying your particular skill set in the right setting, at the right time, with the right people. Some people knock it out of the park or get lucky early in their career. For others, it takes a few trys.
Whatever your situation is, be patient. Keep focusing on learning and adding value. Your time will come.