Still Can't Shake My Crush from School Days

It's been decades since I last saw her, and yet, the thought of Elizabeth still makes my heart flutter like it did when we were in our 20s. We'd chat at school events, but that was as close to a conversation as we ever got. Now all these years later, every memory brings back those giddy, nervous feelings. I know this crush is silly and long gone, yet it won't go away. Is it normal for an old flame to linger like this? Should I just let it fade on its own or reach out somehow?