After the traumatic event, he became emotionally withdrawn and avoided social interactions.

withdrawn 是动词 withdraw 的过去分词形式，withdraw 由前缀 with-（表示"向后、离开"）和动词 draw（拉、拖）组成，字面意思是"向后拉"。 在心理层面，withdrawn 形容一个人"退缩的、孤僻的"，指主动将自己从社交或情感接触中抽离出来的状态。