I think you have a new chapter in your book of life to move into. And he has a completely different chapter of life to move into. I don't think it's personal, but it feels personal. And it would feel personal to anyone in your position. His life has become filled with new places, experiences and people. And he seems to be embracing that. Your life has taken you on a different route, with different places, people and experiences. It's hurtful when relationships end, especially if it was never discussed, no goodbyes were said.

I had a friend whom I visited on a weekly basis for about two years. We talked about everything. She was having a hard time finding a job, so I helped her re-do her resume. She got a job within a few weeks with that new resume. We continued to visit, but much less, since she was working part time. Then one day she moved away from the neighbourhood and didn't even tell me she was leaving. So clearly, we weren't as close friends as I thought we were.

This is the nature of friendship. You will leave people behind. And you will be left behind. The "why?" will never be answered. Even if you ask them "why?" that doesn't mean you will get a desirable answer. So I wouldn't even ask that question, as you might not like the answer. I can tell you this: you will get new friends as you live through your next chapter in your book of life.