I don’t use the terms because too many people use them in too many different ways. I find them too ambiguous. For some people these words hold meanings that don’t apply to my life. I don’t want to use words which could be interpreted as saying something about my personal life that is not actually true.
When it comes to emotional issues, as much as possible, I like to use clear, precise, unambiguous, easy to understand terms. Due to the nature of language, this is never 100%, but it’s easier to do when using words that I and the people in my life have a shared meaning for. (Such as girlfriend, boyfriend, spouse, friend, etc.)
Do you have any opinion about other people using them?
Not much. The context of the words usually tells me what is meant, rather than the words themselves.
How do non-polys react when you use these terms?
In my experience, they thought of a “primary relationship” as something that a person can only have one of, and as the only real relationship.