Yes, it is a bad relationship in the most basic moral sense.
Just as many things are negative in the real world within this series.
Like extreme clan absorption.
Or selfish love to the point one ignores the interests of the one they supposedly care about.
Or child soldiers.
Or basically sealing "nukes" into fellow villagers and dooming them to loneliness.
Or human experimentation.
Or genocide (Danzo and Nagato).
Or lust for power to the point people turn on those they care for (Uchiha clan itself).
Or manipulation.
Or lack of self-accountability (Sasuke, Madara, etc)
And much much more.
^This series is directed towards 12 yr olds as a starting point. Yes, young minds are impressionable. However, everyone reading should know the difference between right and wrong and the universal evils that exist across all cultures. A series like this isn't going to affect a pre-teen or older negatively in a significant manner.
As for your earlier post about SS, Fifty Shades of Grey, and the like- some people just like those types of romances (I don't care for them myself). People like to look for an escape at times via fiction, however, this doesn't mean that they like the same type of behaviour in real life. They'll enjoy what they enjoy. Doesn't really matter at the end of the day and there wasn't really a need to create this thread. Thanks for sharing your opinion, though.