Talking about your feelings is fine. The line comes when you start making demands of the other person.
People also see these things as magic phrases that will solve the problem. They're not. Interpersonal conflicts are complex even at their simplest. So while it is good to know about all of these things, as a tool of active communication, they're often lacking.
Because the goal of a relationship should be to find a person you mesh well together with, not to find someone you can mold into a perfect partner. That's also a serious problem.
People also see these things as magic phrases that will solve the problem. They're not. Interpersonal conflicts are complex even at their simplest. So while it is good to know about all of these things, as a tool of active communication, they're often lacking.
Because the goal of a relationship should be to find a person you mesh well together with, not to find someone you can mold into a perfect partner. That's also a serious problem.