Miss Kenton is clearly attracted to the butler but he is equally clearly terrified of intimacy and buries himself in his work.

buried 是动词 bury 的过去式，意思是"埋藏、掩埋"。 himself 是反身代词，指代主语"他"自己。 in 是介词，表示"在...之中"的状态。 bury oneself in 是一个固定短语，字面意思是"把自己埋进...里"，引申为"全身心投入于某事"或"埋头于某事"。