This is a one-line poem, and its whole weight sits in a single small word: "still." The speaker misses "the days you still cared," which tells us the caring has stopped. Nothing dramatic is described, no fight or goodbye. Instead we get the quieter pain of noticing that someone has drifted away while still being around, or at least still being remembered.
What the speaker feels is a mix of longing and hurt. They aren't just saying "I miss you." They miss a particular time, when they mattered to this person. That suggests the loss is about attention and affection fading, not necessarily about the person vanishing.
The mood is bare and sad, with a hint of resignation. The poem gives us no explanation, no anger, and no request for things to change. Because it says so little, the feeling lingers, and readers can fill the gap with their own experience of someone who once cared more.