Well the main problem Keima is having with Chihiro is this
He just doesn't know what do do with Chihiro so he's hoping that if he ignores the problem it will go away. Plus he has his own feelings to deal with in regards to her.
Based on the last page it does seem like he realises that simply making Ayumi like him more won't work so maybe he'll try and do something about Chihiro. He might just come clean with her and explain everything but that doesn't seem to be his style.