You said "she believes she had probable exposure in two non-emergent surgical cases." By "non-emergent," do you mean the people that only later showed Covid symptoms but were asymptomatic at the time of the surgeries in which she assisted? And that now with 20/20 hindsight and because you were "getting it out of her," she thinks this might be where she got exposed? Or did she think it at the time? (But why would she think it, if they were "non-emergent"?)
It seems like the core of the argument is what she knew and when she knew it. If she knew at the time that she was being exposed, she should have jumped on any early symptom and gotten tested immediately, while being careful not to expose anyone else. If she only guessed later that these cases might be where she got exposed, but didn't know at the time that they were ill, she had no obligation to quarantine until she showed symptoms. She has a high-risk job and works in a place where Covid cases go. If she was to have to quarantine every time someone in the room might have Covid, she would not be able to work.
Yes, once she began to be symptomatic, she should have thought of Covid, and tested and taken precautions and stayed away from you. (Frankly, with your jobs you two should probably not be living near each other anyway.) I'll add, however, that if her primary symptom was being exhausted, that is so much the norm for doctors that it wouldn't be surprising if she didn't think it meant anything new. It would be easy to overlook that exhaustion might mean Covid if you live with exhaustion all the time.
If she had other symptoms and didn't test, that is where you would have the beef with her, for your own sake. You are asking for help to "understand if the behavior is acceptable to me in my chosen life partner." It sounds like you're saying "the behavior" is that she deliberately misled you. Maybe she did, maybe she didn't. If she didn't, it shouldn't affect your opinion of her as a chosen life partner.
I will only tell you what the protocol was way way back in the way back machine when the virus was new to us. At that time, anyone in your SO's profession who was working with covid patients were self-isolating. In New York, when it was bad, they were living in hotels so they wouldn't infect anyone else. Now, we know more about the virus now, and the PPE problem is less but only in most places, not everywhere, so I assume she is using double face masks and a shield, as this is what is recommended and these things are now available everywhere but in rural areas, at least for the highest risk people like your SO. I mean, I just had my ears cleaned out and have had dental exams since covid and everyone who worked on me was wearing masks and shields there. As to any specs from manufacturers, I don't think you've got that part right -- there is no machinery or device I know of that was designed to treat covid patients. One of the reasons so many died in the beginning is that doctors were killing them by using ventilators too often. They didn't understand the disease yet, and ventilators are not made for covid lungs, they are made for lungs with different kinds of damage. They are too powerful for covid patients, so now they know to only use them if necessary and not to turn them up so high, but again, there is no ventilator designed for a covid patient. We don't even have any medication designed for a covid patient -- the ones they are using were designed for other diseases. So nobody can actually follow a manufacturer's guidelines and properly treat a covid patient; they are intentionally not following those so they don't kill covid patients, and the death rate has gone down considerably since they started doing that. I think the ethical thing to do involved both of you, and that was a sincere discussion as to how much risk both of you wanted to tolerate. You are both in high risk professions, actually, as you are both caregivers. You needed to decide a long time ago if you were going to live apart for the duration of the crisis or take the risk because you wanted to be together. If you didn't have that discussion, both of you are at fault, if we're talking ethics. But there's a second element. As soon as she felt symptoms, she had to quarantine until she either tested negative three times for a few days, or tested positive, in which case she had to quarantine as long as required until she was no longer contagious. I believe that time is some period of time after the more contagious symptoms are gone. Surely she knows that, and you should also know that because of what you do. The fact she did not do that put you and everyone else she came into contact with at a very high risk of infection, and there is no excuse for that at all.
It just seems to me that if my husband and I had a clear agreement that I would tell him I had a possible exposure as soon as it became obvious to me, and then I didn't do it, my husband would have every right to want to know why, without dragging questions of professional ethics into the conversation. He would have the right just because we had agreed. It would not be necessary for him to bring up questions of professional ethics, since me breaking my word to him was the issue.
However, if we had not really talked about what we would do if one (or the other) suspected we had exposure but thought it could be something else, (or even simply, if one was sick with Covid but had lost the ability to be aware of it -- Covid is known for causing brain fog), it seems that the other partner doesn't really have much right to act like it is a broken agreement. You have to have an agreement before someone can break it.
From what you are saying, it doesn't sound like your partner knew for sure she had Covid and hid it from you -- it sounds like she either wasn't sure or it just overtook her. If she was too exhausted to rinse her hair, she might have lost track by then of the obligation to communicate or even the ability to do it.
That all said, however, it sounds like you are reacting as though the two of you had at least a tacit agreement she would tell you if she wondered if she had gotten Covid-19. It would be more surprising to me if a couple didn't tell each other such things (even as early as when it was just in the worry stage), than if one person did tell the other. I tell my husband every uninteresting detail about my health (as he does with me, too) from the moment of the first scratchy throat or stiff shoulder from sleeping funny. This is kind of a bellwether for communication between us -- he's always interested and would want to know. If your primary issue here is that you think this is a pretty dang big thing for her to have failed to mention (even if she thought it was probably nothing), I'd think so too. Communicating constantly (even about unimportant things) seems to me really significant in a relationship.
Unless you are saying you would not marry her
because you are upset with her about medical ethics, I would drop the ethics line of the argument, and instead talk with her (when she is better) about the communications side of things. She might not have confidence that you are interested in what she says even if it's humdrum; if so, it's time for reassurance and support. But if she is just not interested in having this level of communication, and if it is important to you (as it would be to me), you and she do sound like you have some talkin' to do. Just not while she's ill.
Good luck to you both, and I hope you yourself did not get Covid. What an awful illness it can be.
I assume you're really angry with her from the way you are talking ("high-risk Covid cases", "I got the info out of her", "ethical?"), but it is a bit surprising. I assume you knew she was an anesthesiologist long before this.
A lot of doctors who have died from Covid-19 have been anesthesiologists, because they are the ones called on to knock people out who need to be intubated, and the patients are coughing and gasping for air while it is happening. If she is your significant other, you must have known that with her specialty, she is always at risk.
I don't know what you mean by a "high-risk" Covid case. Your s.o. could be exposed to a coughing, hacking person and not get sick, if her PPE was good enough, just the same as she (or you) could get ill from someone who doesn't even look sick. There isn't a strain of Covid that is higher risk than other strains of Covid, it's all the same risk and just depends on who the virus hits, how seriously it will take hold.
If she had the agreement with you that she would tell you every time she came into contact with someone who had an extremely serious case, and she didn't tell you, possibly it's because she would be telling you all the time. I think that in order to do these high-risk jobs, the people doing them try to let the concerns of themselves getting the illness become background noise, or they would possibly get too panicked even to do their job. But that said, if you had an agreement that she would always tell you if a particular case was really serious, and if she knew the two cases were very serious and her PPE was unlikely to protect her, I'd say you have the right to be angry for your own sake.
But if you are going to hurl accusations of ethical breach at her, I'd remind you that it would be unethical if she had not treated the patients, and that she behaved ethically to treat them. She sounds like an ethical doctor.
Anyway, you're assuming she knew she was dealing with cases of particular significance in terms of her risk of getting sick, which I don't think you can know. And then, she got sick. She should have told you when it became clear to her that she really was sick with Covid-19 and not a cold or the flu. She has doubtless had so many opportunities to get sick, and had to wait through smaller things to be sure it wasn't Covid, that it does seem reasonable for her to only tell you when she knew she had it. If that is when she did tell you, it doesn't serve any purpose for you to be angry at her for not telling you earlier that she was exposed to two particularly sick people.
Since you work with high-risk elderly and she is an anesthesiologist who by the very nature of her work will be exposed to Covid-19 probably every day, you need to decide if you want to be with her or not. And if you do, getting mad at her for getting ill with Covid-19 is not likely to enhance your life together, so think of some other way to make practical acommodations to the risks of her job. And please remember, Covid-19 is not easy to have, even if you survive it. She's sick. Don't yell at her and try to one-up her with stuff like saying she was unethical. That claim (involving outsiders) has no place in a disagreement between the two of you.