I find it incredibly funny that Harry is more afraid of George and his needling than he ever seemed of Voldemort! It's probably the unspoken threat of George dropping a hint to Molly that something's going on between Harry and Ginny and the fact that Harry knows George would actually be "evil" enough to actually do it!
I love this chapter for several reasons. The first is that what started out as Ginny's attempt to prove to Draco that she and Harry are truly together turns out to be an extension of friendship to Astoria and therefore, Draco. The second reason is that Ginny's invitation forced a difficult conversation to take place between the friends and that they acted like adults rather than school children five years younger. Finally, The party gives Harry the opportunity to observe how his friends are coping with the aftermath of the war: the gaps in circles, those who avoid uncomfortable subjects or people, or the intense need for close physical contact. I'm glad that Draco seems to be coping with the house full of Gryffindors well enough to stay until midnight after Harry promised to look into the attack on Nott. Like Harry says, it's going to take a while for attitudes to change and it seems that his guests are taking their cues from him as to whether or not to accept the Slytherins. I'm sure he's grateful to Lisa for breaking the social ice and coming to talk with Astoria.
All in all, this is one of my favorite chapters. Well done!