I think that yes, "pull yourself together" is probably considered offensive these days.
I have to say, the people I see that "can't cope" are very protected in their MC bubble and supported by parents who perhaps enable/prolong this attitude.
I see it occasionally in my friends husbands/partners, it's very rare, and I have to say it's not really tolerated.
It has lead to divorce because I don't think the type of friends I have as willing to sacrifice their own happiness and the ambitions they have for their children to grow up with actively interested parents who the children can rely upon to prop up someone who has become a stranger to them.
I don't think I've ever seen it from a mother of my generation.
I would question why one adult should long-term sacrifice their quality of life for another adult, and what the benefit of this is. Short term, completely different and I would expect in a long relationships this could potentially be the situation at one or more points and a reason/benefit of being a long term relationship.
So I do wonder if the supportive system around people does dictate how much they get to opt out.
I've definitely had my own difficulties and struggles (I'm ND which has had a big impact on my life) but I was born into a family where no one could be relied upon to support me (lots of MH/ND) so I'm not unsympathetic, but this is my personal observation from my little corner of the world.