Alright, well working hard makes me happy, makes me feel good, and it's something I would respect in a partner.
Fair statement. Anyone who finds genuine personal happiness is self-evidently in a good place.
I fundamentally reject that. Working hard doesn't make you happy; it keeps you busy and it stops you thinking about much (including maybe remembering you're not happy), but that's not the same thing. Doing something you enjoy, yes, that does make you happy, but that is decidedly unrelated to work ethic and any overlap is more coincidental than not, IMO. I agree that someone should do a job they enjoy, of course.
This a thousand times over. I agree 100% mate.
High-five, dude.
Well, later maybe. I'm feeling a bit tired & lazy to high-five right now.

"Work ethic" is not about enjoying the job you do; it is about the moral benefit accrued from work itself, and the alleged benefit to one's character from working hard. It's essentially a Calvinist Protestant belief that hard work is required for salvation, though can often be expressed in secular terms these days (the idea that working makes you happy, essentially).
I fundamentally reject that. Working hard doesn't make you happy; it keeps you busy and it stops you thinking about much (including maybe remembering you're not happy), but that's not the same thing. Doing something you enjoy, yes, that does make you happy, but that is decidedly unrelated to work ethic and any overlap is more coincidental than not, IMO. I agree that someone should do a job they enjoy, of course.
It's ideal if you can do a job you enjoy--but to be blunt, not everyone gets that opportunity at every point in their working life.
This is true, but this doesn't mean that one should accept that status quo, and I would argue that the priority in that situation would NOT be to knuckle down and keep going, but rather to seek fresh, more enjoyable employment, since that would be most likely to yield the greatest long-term pleasure.
I personally would not wish a partner to continue working in a field or job that made them unhappy out of a misguided belief in work ethic. I'd prefer they formulated a plan for getting out of it and doing something they enjoyed. Even if it failed, at least they would feel like they'd tried, rather than successfully sticking with something they disliked out of a sense of duty. I suspect that such an honourable failure would sit better with them than a pyrrhic victory.
These are NOT bad things, as you seem to have painted them out to be.
I would say that someone sacrificing their own happiness in an attempt to please/provide for others is likely to prove a failing proposition in the long term. It's quite stressful to maintain the sort of cognitive dissonance required to do that.
Not saying that it can't be done in the short term - human willpower is rather powerful, so of course one can suppress the frustration at doing a job they find dull as dishwater in the short term. But I doubt such application is likely to breed happiness in the long-term future, regardless of the motives underpinning the application of said willpower.
That's what I mean when I say that I find work ethic self-defeating. Working hard because one genuinely enjoys the underlying work is a wonderful thing, of course, but working hard at something one does not enjoy, out of a sense of duty to provide for others, is a task worthy of a saint and inherently stressful to most people. I fear for the sustainability of such an arrangement for both the individual and the partnership involved and would not consider making that sort of sacrifice unless the Sword of Damocles was hanging over me.
Naturally, one is entitled to seek whatever traits one wishes in partners. I'm not judging you for that, so please don't take it that way; I have nothing to gain by doing that. I've tried to de-personalise the above comments as much as possible, using one not you, etc, etc to make that clear. I am commenting on whether I feel it's a good thing in the abstract, and outlining my reasons for feeling that way. Perhaps ever-so-slightly off-topic if being terribly pedantic about these things, but within the natural marginal topic drift for Misc, I feel.