Was there any basis for your assumptions around English?

Yes, I think that's why I am not invited. I have no proof but it's the only reasonable explanation I can find considering the context.

For my assumptions about English, I got hired with them knowing I did not speak Dothraki and they told me it's was not a problem because we would work in English

Loyalty is good, mental health is better. There is nothing, absolutely nothing unethical about looking for other positions. However, I suspect you would profit more from working on your issues (maybe with the help of a good therapist). If colleagues exclude you from work related conversations (probably mostly unconsciously), the proper response is to speak up and address this behavior. Alternatively, if you are not confident enough to do this yourself, you should talk to your manager. You shouldn't let this go so far that you need to have a cry in the bathroom. Deal with it much earlier.

@Roland I am going to therapy but it is quite a slow process. I also did not realise it would have such an impact on the long run. But good point, I will keep that in mind for next time

You shouldn't worry at all about what will happen to Alex or the project. It is not your problem.

Did you discuss this with your manager? If not, why not? If you did, what did she/he say? Or are you looking for a solution which bypasses your manager?

What do your mental health professionals say about your language and job issues?

@Abigail I don't have a manager, we are in a flat structure and the only person above me is the CEO. So I did not talk to them about it, because it seems like escalading too much (maybe I should add that in the question)

@JoeStrazzere very correct that I can't expect them to speak only English. However, they did say all the work things would be in English, so I thought it would be alright. But yes, I should find myself a non-Dothraki job definitely. Moving to another country is not possible for me right now but I hope it will be in a few years. Will start applying for jobs again and hope for the best.

"Getting fired would allow me to get a bit of peace of mind to find another position" - Why do you feel like you need to be fired in order to find another position somewhere else?

"I usually try to say a few things in English for them to realize that I am still here, but they ignore it." - Then you need to be more direct. Be polite but firm. "Do you mind if we talk about this in English so I can follow more easily?"

@Brandin because I feel a bit guilty about wanting to leave the company that offered me a job right after graduation. Also, if I am fired I would have a bit more time to find a position, whereas if I quit I will need to have a new job lined up. Yeah, I think I don't have a choice other than being more assertive

@Rose You think talking to CEO (who is effective the person you are reporting to) is escalating too much, but you're ok with getting yourself fired?

@Rose not sure what country you are in, which seems relevant to culture. I'm from the Netherlands, maybe not considered north, though many northern countries are very social and accepting. You should try to mention that you would like to join in on the conversation, in my country it's rude not to speak english with an non-dutch speaker around, this might be the same for you. I also wonder if you already know 20% of the language (which I doubt because that would mean you could follow huge parts of the language), if it won't improve overtime by learning when overhearing?

I would guess they expected the language problem to be short term, you would learn dothraki before long.