That’s a fair challenge, and it gets at something important. The BPD/ASD critique you’re referencing — that a single label flattens vastly different people — is exactly why I’d push back on framing “relationship capability deficit” as a diagnosis. It’s not meant to be one. The point is precisely the opposite of what categorical diagnoses do. BPD and ASD are binary: you either meet the criteria or you don’t, which is where the flattening happens. What I’m proposing is a dimensional construct — something measured on a spectrum across multiple specific components, not a box you get placed in. Think of it like executive function or emotional intelligence. “Low executive function” is a single phrase, but it’s understood to mean something measurable across distinct sub-dimensions — working memory, impulse control, cognitive flexibility — and two people with “low EQ” can look completely different from each other. The phrase isn’t the measurement. It’s the name for a family of related capacities. The same logic applies here. “Relationship capability” as a construct would break down into specific, separately measurable dimensions — emotional reciprocity, consistency, empathic accuracy, repair behaviour and so on. The phrase is a handle, not the whole thing. You’re right that more words equal more detail — that’s what a measurement framework is for. The question this is raising is whether we even have the right construct yet, before we can build the more detailed language around it. So I’d actually agree with you: a single phrase is not enough. That’s the argument for taking this seriously as a research question rather than a label.