Why do I miss the idea of them more than I miss them?

When signals are unclear and there are long gaps, you fill the silence with imagination: what they meant, what they'll say, the future you might have. Over time that version of them gets more of your attention than the real one ever had the chance to. So the ending hurts twice, losing them and losing the person you built, and the second loss is often bigger. It helps to write down what they actually did, and what you hoped they would do, side by side.