I think that is what Lupin meant when he said he hoped his son would understand that he died trying to make a better world for children to grow up in. Difficult choice, though.
In my opinion, Tonks was basically selfish. She didn’t want to live without Remus, but she had a responsibility that she should have lived up to.
That's the choice men have always had to make, when they go to war. Tonks, OTOH -- that's a more modern aspect of the choice.
Rowling writes about choices, and the fact that choices always have consequences. Being a woman doesn't change that fact.
In the case of Tonks' final battle, Rowling pounds home to us the true nature of the decision faced by a woman soldier. A "surviving Tonks" would have been sad, but it would also have been a cop-out -- a sentimental lie that even in battle, women are somehow protected from death, and that they can go back to their babies when it's all over.
Killing Tonks says that battle is no respecter of whether a woman has kids back home: battle is battle, and people get killed in battles no matter who they have at home.
Dunno if I'm reading more into Tonks' death than Rowling put there, but that's what it says to me.