No judging about the panic attacks from me. Lora used to pull the same shit. She also does get legit panic attacks. I also get legit panic attacks (though far far far more rarely than I used to). It was absolutely amaaaaaaazing the number of times that she and Jon spent part of the day together, and all seemed well, and quiet, and tranquil, until he started to spent the other part of the day with me. And then suddenly, a panic attack. Or HUGE sobs. And then of course, he'd have to go and comfort her (and I'm not actually saying that sarcastically, of course you're going to go comfort the partner that is freaking out). And then the time that was supposed to be me and Jon spending time together turned into the three of us spending time together.
And vice versa - if it was a day when Jon was going to spend part of the day with me, then part with her. Panic attacks, or other freakouts that turned me and Jon's time together into group hangout time, and then of course, she expected to spend the time that was supposed to be just her and Jon still as her and Jon time and not time all of us spent together.
It made me SO ANGRY because I hate calling bullshit on someone else's mental problems, but still, the way it turned out SO many times...my gut screams that those were not all genuine panic attacks, if any of them were.
Anyways, back on topic, thank you for explaining more deeply, and yes, I'd be super-pissed too if I it had gone the way you are describing. Honestly, if I were in Ethan's position (and I did this with Jon and Lora), I said "Hey, it seems like these panic attacks are really bad. What are you doing for them? How about some therapy, or anti-anxiety meds, are you going to the doctor?".
In my situation (and it sadly doesn't seem like this applies to you), I made it clear to Jon that if a large portion of OUR time turned into "group hangout time", then he and I needed to have time together either another day, or his and Lora's alone time needed to be split between "me and him" time and "him and Lora" time. I took the tack of "I really feel for Lora and her panic attack. And when she's having one, I absolutely see how you need to support her then. However, you and I still need time to nourish our relationship and have time together, so we need to reschedule our "us time" to do that. I'm feeling disconnected to you and unhappy, because we haven't had that time to connect and I want to fix that before it gets worse".
And we did. Sigh. Not to gloat, but the first time that Lora had a panic attack that magically improved once Jon was paying attention to her, and then he said "are you feeling better now?" and she said "yes, I feel sooo much better now" and then HE said "ok, well, Liz and I really need some alone time, so since we've all been hanging out for three hours, I'm going to spend the next three hours with her, and then the three after with you"....oh, the look on her face. Because she KNEW she couldn't go from enthusiastically saying she felt so much better to having another panic attack the moment that Jon and I were having alone time without him starting to question it.
And that was an important aspect of why things worked out in the end for me. Jon both listened to my need for alone time with him (and agreed with it) and though he'd take something like an initial panic attack at face value, he WOULD have make the connection if Lora had had another one after saying she felt totally better.
Would Ethan do the same? Or do you think he'd cater to all the panic attacks and not be willing to tell June that you and he DO need some alone time to nourish your relationship? If you wanted to salvage anything with him, I would suggest (if you haven't already) talking to him about needing time alone with him to nourish your relationship together.
And hell, if you have a hotel room, then you actually have a great situation where he could spend some evenings/nights with you. You'd get your alone time with him. You wouldn't be in June's home, making June unhappy. And you're still there for only so long, since it's for work, so (in theory) June would be able to grit her teeth and deal with it, knowing that you're only going to be around for so long, before heading back home.