Is this a symptom of mental illness

[Navigatingarelationship]

When someone takes the last interaction with their DH or SO to base their entire experience of the relationship on, is this a symptom of mental illness or personality disorder?

What I mean is, if there was an angry exchange of words but the relationship was otherwise great, the person would use the angry words to think the entire relationship was flawed.

Not sure I'm explaining this right. It isn't about me but someone I know.

no, not really

No. It may be an example of cognitive bias; such as catastrophising, or black and white thinking.

Well no because
say those words were "I’m gonna smash your face in" or "I always fancied your brother more" or something equally significant … it’d have huge relevance to why they were the last words of the relationship wouldn’t it?

Not necessarily, no, but what to others sometimes seems a total overreaction to what on the surface was a one-off disagreement, and a nonsensical over-the-top reaction based on how you perceive their ‘norm’ or past, might in reality be a last straw scenario for whoever is on the receiving end of it, or even the excuse to justify leaving or their own bad behaviour that they were waiting for.
Just because another couple’s relationship has always looked great from the outside doesn’t mean it always was or is. Resentment can burn silently and unseen until what seems the slightest thing finally makes it bubble up to the surface.

Yes my ex was like this to an extent and, in hindsight with him now knowing he has various deep rooted mental health struggles, believe it was due to them. Not sure “mental illness” is the right wording though.

There is no mental illness that has those things as diagnostic criteria.

As to something judging their relationship by what happens in an argument It entirety depends on what is said in the angry exchange of words, or how often these exchanges happen

For instance If the words are name calling, abusive language, saying things to purposely hurt then it seems reasonable to judge the whole relationship on that

What happens in angry exchanges is not exempt from the relationship....

Also it depends if there is apology , ownership of the anger and repairing of the relationship after the anger.