I'm not sure what you people are expecting from this manga. Do you not realize that Chi is, like... right there? In every chapter?
Say we have a chapter in which Chi's not around and Nishikata straight-up shoves his tongue in Takagi's mouth. However satisfying that might be to watch, I don't think it would have much to do with the theme. This is a manga about Takagi teasing her husband and daughter, much like the original.