They miss you. Avoidant attachment is not the absence of attachment. It's an attachment system that learned closeness comes with a cost, so it manages connection with the emotional thermostat set low. The bond forms the same way anyone's does. What differs is what happens when the bond starts to feel risky: the system deactivates, suppressing attachment feelings instead of expressing them.
Suppression is not absence. Research on deactivating strategies shows avoidant people can keep attachment feelings out of awareness while conditions are calm, and that the material resurfaces when the suppression effort drops. Missing someone is exactly that pattern in the wild. While the relationship felt close and demanding, their system was working to need you less. When you're gone, the work stops being necessary, and what was suppressed gets room to move.
This is why "do avoidants miss you" has a yes with an asterisk. The feeling exists. The expression is delayed, muted, and frequently routed through low-stakes channels, a meme at midnight instead of a phone call that says the words. If you only count the phone call, you'll conclude they feel nothing and be wrong.
