4. In one of the few moments in the entire book, there is some focus on Harry and Ginny’s relationship in this chapter. After interrupting a kiss between the two, Ron berates Harry for “messing her around”. Was Ron justified in this argument, knowing what Harry had to do to defeat Voldemort, or was this a just a case of an overprotective older brother? Do you think Ginny’s other brothers would have had the same reactions?
It is interesting to compare Ron's reaction to Harry kissing Ginny to his earlier reaction to Ginny kissing Dean. I think Ron, while he may be clueless about women, gets it. In the earlier incident, Ron explodes at Ginny because I think he knew exactly what she was doing. Ron is right in that scene about what Ginny is doing (but oversteps his role as her older brother). He targets Ginny not Dean. He knows who has the real power in that relationship, and it's Ginny. He may also know that Ginny does not love Dean and he's basically recognizing the same behavior in his sister that he will later display himself with Lavender. How much Ron is aware that Harry is taking interesting in his sister is not really known, but it is possible that he is picking up on it. The irony is that Ron goes off and does the same thing Ginny is doing in his own attempt to make Hermione jealous.
In this scene, Ron switches sides. He doesn't go after Ginny as he did before, blaming her for leading Harry on. He assumes that Harry has the power in the scene, though we know that it was Ginny who took the initiative. Why did Ron switch sides and blame Harry for messing with Ginny? Again, it could be that we are able to get a deeper insight into what is going on with Ron. Ron is in love with Hermione, but has not been able to express his love to her. Now he finds Harry, who has made it quite clear he is not going to be pursuing Ginny, doing that very thing. Of course he's going to explode at Harry - some of it may be an expression at his own frustration in not being able to follow through with his own desires for Hermione. The other thing is that Ron may believe in his heart that Harry is not going to survive and that this is a cruel thing to do to Ginny to get her hopes up that they will have a future, when Ron (and not without merit) may believe it is unlikely Harry will survive their ordeal. We get a twist on that later when Ron and Hermione finally do follow through with the desire of their own hearts and Ron makes the humorous comment of basically it's now or never.
5. When Lupin and Tonx arrive at Harry’s birthday party, Harry notices that Tonx looks “radiant” while Lupin looked “unhappy”. Later, as the Minister of Magic arrives, the pair leave quickly, saying “We shouldn’t be here”. Given that Tonx is a Ministry employee, it seems odd that she shouldn’t be around the Minister. What did you think of their behavior and Lupin’s statement?
I had suspected that Tonx might be pregnant because of the way she looked at Remus when she arrived back at the Burrow following Harry's escape from Privet Drive. We have learned through her Aunt Bellatrix that her marriage to Lupin is considered to be disgusting in Wizarding Society (a view not just held by Slytherins). That view is similar to the view held, even to this day by some, of interracial marriages. Such marriages were shunned by society, black and white. For a long time those marriages were even illegal. Often those who would defend the bigoted view would use as their defense "what about the children" and how such children would suffer in society. We learn that even Tonk's parents are not happy about the marriage and of course later on we see that Tonx is targeted by her aunt personally because of what she's done.
What we see here, then, is that the couple have risked everything to marry and while Tonx doesn't seem to care, Remus - who has lived with his condition nearly his whole life - knows exactly what this means and he does love her. He does know what suffering comes not only to his wife, but to their child. Tonk's happiness and Remus' unhappiness are both born from their love for each other, showing itself in different ways.
If the Ministry finds out that Tonx is pregnant it is not clear what the Ministry might do about it - but we can imagine what might happen and so they flee. I had not thought, until I read the other comments here, that Tonx may have been sacked from her job as an Auror. Certainly the Minister of Magic is her former boss since he was the head of the Auror Department. We are seeing evidence of a subplot between Scrimgeour and Tonx - who might be made an example of what happens when one breaks the rules, written and unwritten. If we draw the parallel between Tonx and Remus' marriage and interracial marriages in the past (and in some places still today) we may see why the bigotry goes so deep.
We can also imagine that in the past Scrimgeour and Tonx have had to deal with Greyback in their roles as Aurors and Remus Lupin is an exception as to what the Wizarding World sees as what happens to people when they become a werewolf. Werewolves are a threat to society - and to children in particular - and one could make the case that from Scrimgeour's point of view, Tonx has betrayed the trust placed in her when she became an auror.
Finally, they are both known to be in the Order of the Phoenix and their allegiance lies elsewhere and not with Scrimgeour. He may see this as a threat to his own authority. This is supposed to be happy day for Harry and the last thing Remus and Tonx would want to do is spoil the party. And so they flee.