They left the party early. I don't blame them - it was getting boring.

I 是主语代词，指代说话者自己。 don't 是 do not 的缩写形式，表示否定。 blame 是动词，意思是"责备、责怪"。 them 是宾格代词，指代前面提到的"他们"。 don't blame them 这个短语表示"不责怪他们"，表达对他人行为的理解或宽容。