The Forgotten Birthday...

So...I had this friend since childhood, let's call her Mary. We grew up together, shared all our secrets and dreams back in the day. She moved away for college when she was eighteen, but we kept in touch through letters, phone calls... Later, she even visited me every year on my birthday to celebrate...until last year. Last year, I decided to go somewhere nice just because it was her turn to come see me. But she didn't show up...I waited and called her a few times but never got an answer. So sad... Fast forward another year, now I'm turning fifty-two tomorrow. I haven't seen her since then. We've talked online a couple of times but it's just small talk, nothing like our childhood days. But here comes the thing...I saw Mary's mom in town last week and she mentioned that my birthday is coming up soon and how happy she was that Mary had planned something special for me. I was shocked because Mary never said anything about this... So, now I'm all worried that she forgot or maybe even canceled whatever plans were made. She's probably busy with her own life now, which I totally understand...but still, it hurts a bit. Am I overthinking this? Is it normal to feel so let down when someone you once cared about doesn't celebrate your birthday anymore? Do I just need to move on and accept that people change as they grow up? It feels like part of me is stuck in the past where we used to be inseparable friends, even if she's moved on with her own life. What do you think...?