Middle-Aged Melancholy...

Every day I see her walking the dog around 4 PM, and my heart sinks just a little bit every time. She's my ex-wife... or at least she was three years ago when we finally called it quits. The breakup wasn't ugly; in fact, it felt more like a mutual agreement that we'd been drifting apart for so long that there really wasn't much left to salvage. But watching her now, walking our old neighborhood streets with someone else's dog... I feel this strange mix of sadness and something I'm not sure how to describe. Maybe nostalgia? Or just the pain of knowing things didn't work out the way we both hoped. Every time she looks my direction, even if it’s only a brief glance before turning away again, there's an emptiness in her eyes that makes me wonder... did she ever really think there was someone else for her too? Do people just fade into each other’s lives like this after something ends? Am I the only one who feels this way? Sometimes I look at all these couples still holding hands and laughing, and it’s hard not to feel a bit lost. Is it normal to still have such strong feelings three years later... or am I just fooling myself with memories that aren't real anymore? What do you think?