As is often the case, though, the mood swing has gone too far. 不过，与过去常有的情况一样，人们的情绪波动有些过头了。

Maybe, his apathy signals he is at the negative extremity of a mood swing. 或许万念俱灰只是他情绪波动的一个极端吧。

2. has something to do with 和……有关

Someone I care about is in trouble, And this club has something to do with it. Now knowing my father was a member, It only stands to reason that his closest friends were, too. 有个我关心的人遇到麻烦，和这俱乐部有关。我父亲曾经是会员，显然他最好的朋友也是会员。

We really don't know, but it has something to do with "being." 我们并不知道，但它是与某种存在有关系的。