Everyone has an opinion on Tonks' feelings for Remus, but she doesn't particularly want to hear them all. Of course, that's never kept some people quiet.
If you had told me, even as recently as a year ago, that I would feel even the smallest twinge of sympathy for Remus Lupin, I'd have told you to have your head examined. As it is, watching the pathetic wisps of your new, not so corporeal Patronus fade into the darkness, watching the self righteousness anger on your face, I can't help but feel pity for the object of your obsession.
It's an odd thing to say of a werewolf, a savage beast that would eat anyone in its path given half a chance, that he is too kind. Or perhaps it's merely that you have the entire, idealistic, overly romantic, blind Order to back you and your tale of unrequited love. For a Gryffindor, he's always been quite timid when it came to how others view him, so afraid that everyone will go away and he will be left, the lone wolf.
I, of course, don't have that problem. That offends you, doesn't it? You want so much to believe in your pathetic little crush that the very thought of someone who will look you straight in the eye and tell you that this isn't love offends you to your very core. So fortunate for you then that I'm the horrid, nasty ex-Death Eater who treats everyone with the same level of contempt, isn't it? You can ignore me. Even better, you can go crying to your supporters and look sad and mope and they'll pet you and give you the assurance you want, promise that I am just being mean and that your knight in dingy armor will eventually come around.
I have no doubt that he will 'come around,' eventually. He can only hide behind excuses for so long - his age, his poverty, his disease. Faced with the choice of giving in, of giving you what you want and making you smile again, and of standing up for himself and actually telling you what a blind man could see, of hurting you and watching you cry, I have no doubt he'll sacrifice himself for you. Then, you will smile and laugh and say that you were right and you'll still refuse to admit what I've known since the start.
He doesn't love you.
He doesn't want you.
You can mope as long as you want, turn your Patronus into a replica of him naked, hang off of his arm and beg, make him feel as guilty as possible - and doesn't he have a wonderful capacity for guilt? - but he will never love you. You can't even claim that it's because there's someone else. There isn't. It's entirely that he doesn't care for you and your obsession.
Of course, life is uncertain. Perhaps, on that fateful day when you rip through all of his defenses, he'll surprise me. Perhaps he'll earn my respect by looking you dead in the eye and saying 'no.'