Disclaimer: I'm frankly not sure I would want to own such depressed characters.
"Accio Locket! Incarcerous. Silencio. Right, that should shut you up long enough for you to stop claiming I am choosing. Harry, do I have to silence you as well, or are you going to listen to me?"
"I'll take that confused meep as assent. Are you sitting comfortably? Then I'll begin."
"Firstly, Ronald, I consider you both my best friends. Therefore, I resent the implication I have to choose between you because you are in a snit. We agreed to do this mission, and if we don't get it done, then there is no way you will ever be able to go back to your family, or for Harry to settle down. That is what is important, not this bizarre jealousy."
"I have to say it now, I consider you at the moment merely my friends. We are all three close, we work by far the best as a trio, and we are all abysmal at romantic things. Trying to bring that kind of jealousy into a tent this small is highly highly stupid. In addition, living with the two of you in small quarters for the last few months does not endear me to either of you. In the long run, we are all going to want partners we can discuss our interests with, and I hate quidditch and both of you have only ever understood my bookish tendencies when the puzzle of the week needs solving. In addition none of us have the tendencies to be even vaguely romantic to the others. So leave it. We are friends. And friends stick together through the awfulness of the war. We can find a partner each when this hell is over. Or, if you two really want to explore why Ron was Harry's most missed thing feel free… "
"No? Judging by the looks of horror on your faces a trio of friends it is. Excellent. On to my next point then. Family. Ron, you just accused us of not knowing what it's like to be worried about family, and you, Harry, have spent ages whining about the "excessive" protection the order gives you. Well stop. We all have people we care about. We've all lost people. At least your parents aren't going to hate you, Ron, if we survive all this. How exactly do you think parents who have little idea of the war are going to react? And, at least the order protected you Harry! I have to say, despite your various attempts to demotivate me, and your failure to defend me just now, I have been rather important to your plans. Or would you like to be hiding out with only your dress robes?"
"So, I would say I am rather likely to be a target, even without my wonderful blood status. But the order didn't even vaguely try to protect my family. I know they have safehouses. I asked, but apparently it isn't worth saving Muggles. So I had to watch my parents not recognise me. So, stop your unsympathetic whining. We'd see in a paper if your loved ones were found. They are purebloods, and Snakeface is rather more squeamish about spilling your lovely pristine blood than my earthy hued vitals"
"Right, you've listened. Good. Now we are going to try something radical: a new plan. I don't think this is working. So, maybe we try polyjuicing ourselves again, head into non-magical territory, and find a museum. They might have records of founders' objects. The British Isles is huge, and if we don't use magic, I'm sure we can get away with selling some slightly melted galleons to cash for gold, and buy some proper food? Any arguments? No? Good. I'll take first watch."