Like... wtf is wrong with this authors?
Kokoro was a nice character and even her liking him wasnt a problem. Its sad but she had plenty of time while she was waiting for him to magically like her and now that he likes someone else she does that? Way worse than what Raizou did so far. Not to mention is absurdly selfish and completely disregard the feelings of someone she was suppose to like.
And of course by mistake Riku "found" the shrine of Raizou family and by mistake she sees them kissing... its all so unnatural.