Since the release of Half-Blood Prince, there has been a lot of unrest in fandom about the way the Remus/Tonks relationship is played out in the Hospital Wing scene in Chapter 29. Many feel that Tonks acted inappropriately in this scene, is a "bad role model" for girls, and her love for Remus is one-sided. This has caused many fans to strongly dislike both HBP!Tonks and the Remus/Tonks pairing.
Apparently, there are even those in the fandom who, based on their interpretation of this scene, feel Tonks couldn't even care less that Dumbledore is dead, and is thus the most selfish character in the book and does not deserve Remus, much less any fan support.
Huh?
This opinion appears to come from the part where Tonks declares her feelings about Lupin while he is broken down over Dumbledore's death ("This is not the time to discuss it...Dumbledore is dead"); later, Tonks sports pink hair at Dumbledore's funeral.
How can Tonks dare to be so happy and un-mousy when Dumbledore is dead? What nerve of hers!
McGonagall has the answer to that right here in canon: "Dumbledore would have been happier than anybody to think that there was a little more love in the world." I guess people have forgotten that this is Albus Dumbledore we're talking about--NOT your average wizard. Would Dumbledore have been offended by Tonks wearing her pink hair to his funeral? No. This is the same man who allowed Harry to chew him out at the end of OOTP; the man who showed a wicked sense of humor wherever he went; the diplomat who always accepted people for who they were. Dumbledore would be relieved and happy that Tonks is feeling better and has her metamorphing ability back. He would also be delighted that Tonks and Remus have found love. (It's pretty likely that Dumbledore knew the whole time that there was something going on between those two, as he tends to be the all-knowing sort.) Knowing Dumbledore, he'd be disappointed if Tonks didn't have her wacky hair at the funeral.
As for Tonks, does the fact that she's over her depression at the end of HBP show that she's totally unaffected by Dumbledore's death--or even worse, happy that Dumbledore is dead? No. Throughout the Hospital Wing Scene, Tonks is just as devastated as everyone else over the news. But the Order isn't even discussing Dumbledore when Tonks finally snaps! Right before the "I don't care" scene, Molly and Arthur appear and the focus is turned to Greyback's attack on Bill, followed by everyone watching in shock as Fleur tells off Molly. Why is it that Tonks is being considered a selfish drama queen, when Fleur makes as much of a scene as Tonks does in the Hospital Wing? And it is only because of what Fleur says that Tonks feels compelled to bring up her relationship with Remus. She doesn't just randomly bring it up out of nowhere in order to selfishly cause a scene; there is a clear connection in her mind, and thus in the text.
In addition, if any of the other Order members (including Remus) had felt that Tonks' behavior at that moment was completely inappropriate, they would have said something or escorted her out of the room. Instead, Molly and Arthur jump in and defend Tonks' position on the matter, and then the stern, mature Minerva McGonagall puts in the part about even Dumbledore being happy. No one in the Order seems to be disapproving or suspicious of Tonks' actions. Yes, Remus does then try to change the subject back to Dumbledore, but I think that has more to do with him not wanting to discuss a private matter in front of twenty other people, rather than with him thinking badly of Tonks.
So, if none of the characters have a problem with Tonks, why do so many readers?
As for the funeral, Tonks' hair is pink and she and Remus are holding hands for one simple reason: JKR needed to show us that Tonks and Remus are together and happy without going into a long tirade about it. There's no room for it, especially because the focus of the story is now on Harry, and Dumbledore's death and funeral. So JKR just slips it in there, so that we know what happened with that minor subplot. The whole thing is really just a matter of bad timing--yes, I can see how it would be suspicious that Tonks is so happy so soon after Dumbledore's death. But Tonks also knows that Remus is (a) no longer risking his life hanging out with Greyback & Co. and (b) still in love with her. Two major sources of stress for her are now gone. The fact that that was all she needed to get out of her funk may help support some readers' theories that Remus was the only reason for Tonks' depression. But it does NOT show that Tonks is happy about Dumbledore's death.
However, let's forget about JKR's strategy for a minute and just go with the story. Now Tonks, who knows Dumbledore as well as we do, knows that Dumbledore appreciated her for who she was, crazy hair and all. So she has no problem wearing her hair pink for the funeral. She may have also done it as a sign to everyone else that she is okay again, as it was probably the first time that most of the Order has seen her since the Hospital Wing scene. The holding hands part--would Remus be holding hands with someone that he didn't love and was embarrassed to be seen with? No. Give the man some credit. He doesn't seem to have a problem with her hair, so why should anyone else?
(In addition--she's holding hands with him, a rather innocent gesture. She's not hanging all over him. She's providing support for him because she knows Dumbledore was important to Remus. But JKR doesn't have room to go on and on about that. They are minor characters, and the focus at Dumbledore's funeral should be right where it is--on Harry.)
And if Tonks really didn't care about Dumbledore being dead, why would she even show up to the funeral in the first place? Just to show off her new boyfriend? Or her hair? I don't think so. That's insulting to both Tonks and Remus.
Finally, it doesn't say anywhere that Tonks was smiling and happy and perky at the funeral. If it did, that would be a cause for concern. But it doesn't. Again, JKR doesn't need to spell out that Tonks was sad, and Remus was sad, and the squid was sad...blah blah blah. It's not necessary. So it's safe to say she and Remus were just as mournful as everyone else. I'd even be willing to bet that Tonks was dressed properly in modest black attire. (And if she wasn't...I still don't think Dumbledore would care.) But that's another thing that JKR doesn't need to spell out for you.
All the book says is that her hair was "returned to vividest pink." All that means is: she is back to normal. If none of this mousy-brown-depression stuff had happened, her hair would most likely STILL have been pink at the funeral, and no one--character or reader--would have batted an eyelash over it. That's the normal Tonks we all know.