I have been offered a PhD in a European country which I have accepted and I started attending (my first month). However, just few days after starting here, I got another offer (from a different country) with a subject that interests me more (honestly, it's my dream research topic since UG school).
Internally, deep inside me, I want to leave and pursue my dreams and the things I am more passionate about. However, I feel very bad and selfish to do this. The supervisor at the first institution struggled to get me the funding and to get me rolled in without hustle and this kills me morally.
I accepted the first offer because the second one was still too far and I wasn't given enough time from the first institution to wait for an offer from the second one (the subject is also the closest among all others to my interests).
My engagement with the first institution is still on the trial period, in which case I can cancel and leave without any problem.
I don't really know what to do now. I have good relationships with my current supervisor, and he has faith in me. I also have great relationships with the research team. I just don't have enough courage to tell them such a shocking decision.
I want to get some advice, from a career point of view (should I pursue my dream research topic or not?), is it morally acceptable to do such a thing in my case? And what are the possible implications on my current supervisor and the first institution (impact on funding, impact on his reputation, etc.)? What are the possible problems I could face from a legal and administrative point of view?
In case I am advised to leave, what is the best and the least hurting way to tell the first institution and the supervisor? Should I do it face to face or only by email? How will I return back their material without showing my face?
And the last question, what could be the possible reaction of my supervisor?