I'm not sure it's method acting as the thought bubble in the image you used seems to suggest that Elena isnt sure herself that's what it is.
Andrew doesn't fully understand what's going on, but consistently indicates that even the feelings/thoughts/urges are something that he's not "willingly" doing because "Andrew" wants to, but because "Elena" (the character he created) wants to.
Basically, the inner thoughts are truly inner thoughts, but sometimes they have been Andrew repeating a mantra to himself about how Elena
should feel, not how Andrew is feeling about the situation.
Like during one of the first sex scenes, notice how the inner thoughts evolve. "Andrew" is telling "Elena" how to feel, and then the thoughts get so much more willing because it's "Elena" embracing that attitude.
It seems that Elena is now perfectly and completely comfortable playing Nikos's wife as thought bubbles seem to confirm that.
Not exactly. The thought bubbles are initially far more preoccupied about finding out if its a real pussy:
And then Nikos starts demanding Elena say (and effectively think) a certain way:
It's only after being told by Nikos what to think/feel does the inner thoughts start considering accepting this:
So I think it's important to look at the context of those thought bubbles that seem to be "accepting" of being Elena. They're always after being explicitly told to feel a certain way (either immediately, or at some previous point. For example, Elena starts thinking of herself as a cocksucker without being told to during the latest sex scene. But we know that "Andrew" has already seeded that belief way earlier in the first scene).
Ultimately, there's physical and mental feminiztion being done in this story. The mental part is called "method acting" but it's some weird intersection of method acting, split personalities, and some conditioning/mind alteration. We've seen Andrew tell himself how to think/believe. We've seen Nikos and other people do the same.
And really, for me the biggest red flag: Suddenly being unable to speak English and purely speaking Greek:
That really shows how pervasive this mental change has been.
Like I said there now seems to be no more howls of protest from Elena having to wear heels or having to wear revealing dresses or having large breasts as was the case initially.
But getting used to something and not complaining about it constantly, isn't the same thing as accepting/wanting it. I don't complain about having to wear a suit and tie to work everyday since I understand it's just what's expected, but it doesn't mean I want to. At some point, you muscle through it and don't dwell on the things you don't want.
Here's the thing, we don't have the negative reactions ("howls of protests") but we haven't seen any positive embracing either. It's not like Elena has on her own volition gone out shopping for clothes she wants to wear. The vast majority of her outfits are chosen for her and directed by other people. The closest thing we have to that is her wearing lingerie for sex, which is moreso about her trying to please her husband than her enjoying femininity.
In fact the biggest concern Elena had with the doctor wasnt that the changes were irreversible and that Andrew is now stuck as Elena, but rather that Marina was party to what was going to happen. That seems to alarm Elena much more than the shock that she's now irreversibly female.
Why would it being irreversible be a shock? Elena was already suspecting it to be irreversible.
And she calls the surgeries done to her "damage". That's not exactly accepting language.
So I think it's entirely natural for her shock to be that Marina knew. Because she's already been suspecting that the surgeries were irreversible, so being told that isn't new info. But if Marina was privy to that info, then that's not only new info but a potential massive betrayal. Of course Elena would respond more to that fact. It has huge implications on whether she can trust Marina. From Elena's POV, that calls into question everything Marina's told her.