I must agree in general principle.
Besides, I honestly have to admit I don't understood the whole "unhealthy relationship" outcry with regard to this story.
In a world where ongoing conflict has created generations of orphaned children, and those children along with others are in turn trained to be killers who are willing and able to kill or orphan other children, and children like Naruto and Gaara are used as hosts for demons and mistreated because of it, and other children like Sai are systematically groomed to be emotionless bots in the service of questionable leaders like Danzo, and others like Itachi are forced to kill their clans to save a village, etc., etc., etc....
The entire shinobi culture is unhealthy. Killing one another is not an uncommon result of conflict or advancement, is it? Isn't that the point? Isn't that what this last war has been about? How unhealthy their culture has become?
All of that is taken in stride as an accepted theme of the story, but the relationships -- specifically those involving Sasuke (and Hinata) -- are typically scorned as "unhealthy" and heaped with moral indignation. I don't think that makes a lot of sense in context.
No one can find Sasuke more distasteful than I do, but Karin is no paragon of virtue either. I've said it before and I'll say it again: Karin knew Sasuke was a snake when she picked him up. She knows who he is, and what he is, and loves him in spite of it. Maybe because of it. We have no evidence that she wants him to be different than he is, or expects him to conform to some image she has of him.
Beyond a willingness to choose her, Karin doesn't seem interested in changing Sasuke. They are both orphans who took an unhealthy path, both have willingly associated with Orochimaru, neither feel a strong allegiance to anything beyond what they want for themselves. They are dark horses who are as well suited to each other as any other pairing in the story.
Do I think Sasuke/Karin is an unhealthy relationship? From a real world view, yes. From a Naruto world view, no, I don't think it's significantly more unhealthy than any of the other relationships of the current generation.
Has it really been healthy for Naruto to pine over Sakura while she has loved Sasuke? Not only was she clueless about Naruto's love for her, but she couldn't see it because she was stuck on a narcissistic jerk like Sasuke.
Has it really been healthy for Hinata to obsess over Naruto while he has loved Sakura? She nearly got herself killed confessing her love for him, and he has never managed to even comment on it. Meanwhile his love for another girl who loves someone else is as strong as ever.
Has it really been healthy for Lee to be willing to protect Sakura with his life when she hasn't given him the slightest bit of encouragement, and prefers to daydream about a narcissistic jerk like Sasuke?
Has it really been healthy for Ino to feel any emotional attachment to Sasuke, a guy she doesn't really know and who has never given her the time of day?
Has it really been healthy for Obito to have obsessed and fantasized about Rin all these years?
My point is, I personally don't think Sasuke and Karin have a lock on "unhealthy." Like I said, it's a reflection of the world they're living in, and part of what Naruto is trying to change.
Just my opinion.