I do see this pairing working and I honestly have some doubts that Ema truly hates Klavier. More then once, Ema caves into Klavier's pleas for her to do something that she didn't have to do. The two examples that come to mind first are she was acting as security at his concert (Although you could conceivably write this off as her just doing her job, but she could still have passed off the duty to another officer if she truly wanted nothing to do with Klavier) and she also agrees to sing to lyrics of the song in the third case (Something which was certainly not required by anything and would be hugely embarrassing. Had she truly hated him then she would have no reason to concede to his request. And as I recall, she was more then a bit embarrassed after that but didn't really appear displeased which is particularly interesting since this reaction comes not long after Klavier praises her singing).

Now she does show some hostility towards Klavier, but consider her situation. Klavier is the prosecutor responsible for ending Phoenix's career and basically ruining his life. There is no doubt that she respects Phoenix a great deal and even goes so far as to credit him as having saved her. I would imagine that having feelings for the person who ruined Phoenix would feel like a huge betrayal to her, but no one can help who they develop feelings for, so she can't admit it to anyone (perhaps not even to herself) and seems to almost put on a show of being overly annoyed by him. She acts hostile, but there is something more to her treatment of him which is suggested by the way she softens to his advances at times. Of course that is only my own reasoning and no one has to agree.