have a crush on someone 暗恋，迷恋某人

　　e.g. I have a crush on you.

　　Lucky you. 你真幸运

　　have chemistry with someone 两情相悦

　　e.g. I have chemistry with him.

　　We have chemistry with each other.

　　so much in love with someone

　　head over heels in love with someone神魂颠倒

　　Have you ever been head over heels in love with anyone?

　　Tell me about it. 跟我说说吧

　　有时Tell me about it. 也可以表示赞同，类似于“可不是嘛！”