It's more of how Eri is reacting to Tenma in a jealous manner. Logically, the actions in 209 and 210 are understandable without considering negative character traits, but will manga readers actually feel that way? The way they're wrriten, it FEELS like Eri's being cold towards Tenma, even if that's not actually happening event-wise.
Given that KJ hasn't addressed Eri's feelings towards Tenma over the past two chapters, he hasn't really changed his portrayal at all. The only things that we've seen from Eri in 209 and 210 is with regards to Harima.
The only thing that's different is that some people seem to be angry at Tenma turning into a snowman - which was a decision that Tenma made entirely on her own.