A relationship is between two individuals. No matter what happens there, it is entirely that two individuals' issues and has absolutely nothing to do with a third party unless that party gets involved between them. That is a completely different issue all together.
So, whether that the relationship is controlling, it is neglected, it is whatever it is, I don't think it is right and logical for a third party to say much especially when you do not know a single thing. Passing derogatory remarks calling the person either naive or stupid is beyond limits.
It's best that we as third parties keep quiet and not say a single thing unless that person comes to you, tells you the exact situation and ask your opinion. That's different. You are requested to voice out.
The problem with people is that they speak too soon, they speak too wrong, and I guess the worst of all is, the fact that they spoke. They should just kept the mouth shut and say nothing. They are not the ones involved, why being such a nosy person. It's not like without passing remarks as such you will not be able to breathe or eat. You live the same way as you have always been. Furthermore, you are just another person, and not even someone close to them.
Becareful of people like that. They stay single, they, whether intentional or not, love passing remarks that trigger the peacefulness. Maybe, they are just sadists that they love seeing others breaking up. I don't know. Hmm. Thank God I am not close to anyone like that. Phew.