Real love exists and perseveres despite all the obstacles and differences that try to get in its way.
“‘You see!’ said a strained voice. Tonks was glaring at Lupin. ‘She still wants to marry him, even though he’s been bitten! She doesn’t care!’
’It’s different,’ said Lupin, barely moving his lips and looking suddenly tense. ‘Bill will not be a full werewolf. The cases are completely —’
’But I don’t care either, I don’t care!’ said Tonks, seizing the front of Lupin’s robes and shaking him. ‘I’ve told you a million times….’”
— Half-Blood Prince Chapter 29 (The Phoenix Lament)