Abuse is typically a pattern of behaviours and it's also characterised typically with a power imbalance - mostly with the scales tipping on the mans side. Control is usually the main aim.
I don't know what happened to your friend, but she is obviously very emotional right now.
I think like another poster said, a lot of women are waking up to the shit they are given now (not to say that women can't be abusive but by default we have less power in the relationship due to societal factors). If someone calls you a name, it's an abusive act but that doesn't necessarily make the relationship "abusive" on the whole.
Would it end a relationship? Potentially not, could you overlook it... yes probably, but at the same time it's a shitty thing to do even once and the best predictor of future behaviour is past behaviour.
Narcissism is a disorder, although it's also loosely used to describe basically toxic traits in people that reflect certain aspects of narcissim. We're all narcissistic to some degree, but not all people are actual diagnosed narcissists. There is a ton of overlap with toxic behaviour and narcissistic behaviour however so I'm not too bothered by the over use as long as time is taken to actually educate people on NPD being an actual diagnosable thing.
I don't really think we should be sitting here questioning how serious it needs to be for it to be "abuse". There are lots and lots of resources you can look up to educate yourself on what abuse is/isn't rather than posting here and opening up a conversation questioning women for their feelings and asking "how serious does it have to be before you're allowed to use that label".
We should be supporting women not spending our time questioning them. Abuse was normalised, women had no rights. Coercive control was only recently made illegal. Are we seriously having this conversation???