a thorn in someone's flesh （眼中钉）
I wonder why I become a thorn in their flesh. I've never harmed them.
不知为什么我成了他们的眼中钉了。我可从未错待过他们。
我们说的“眼中钉”与英美人讲的a thorn in someone's flesh指的是一回事，虽比喻有异，但意思相同。与此说法相似的还有“刺耳的话”（a flea in someone's ear）。
Dialogue :
Frank: I don't know why I should become a thorn in the John's flesh.
Betty: You mean your boss?
Frank: Yeah. He seems to bear me a grudge.
Betty: That's because you are too much on the ball.
Frank: But why should that make him hate me?
Betty: That's because you put him in the shade.