It did progress...but you have to look at it through Japanese eyes. They are so damn subtle in their relationship cues. If you compare the arc where Kagome was captured by Akago and compare it to chapter 557 (a very easy comparison to do) you will see how much their relationship had progressed. And in fact, it had been progressing even before Kikyou's death.

But we're talking about a culture that didn't have a polite word for kiss until after they had contact with the west in the 19th century...and kissing is still not done nearly as much as is in America, and a language where words like darling and sweetheart had to be imported and still aren't used that much. You shouldn't expect the same type of demonstrative signaling that would happen in an American story -- particularly in a Shonen story.

Shoot, it gets worse in the anime...they even weakened what was in the manga to make it even less demonstrative.

As far as RT is concerned, I think in her opinion, they worked all the bugs out of who they were to each other in chapter 494. That's absolutely the last time Kagome showed any angst about her relationship in Inu.

Definitely easier to do romance in English. The signals are much clearer.