为什么要做对我不利的事情呢Why did you do the things that were harmful to me ? （已近做了）或者Why would you do the things if they were harmful to me？（假设）对...不利：harmful to ...希望对你有帮助
Why did you do the things that are adverse/ harmeful for me ? 恩 对 是harmeful to 差点误导你 多亏下面那位
楼上的说的很对，英语不错哦！