I've pretty much made up my mind about this but would like some other viewpoints. This is the situation:
I applied for PhDs at a low point in my life when I was unemployed and rather hating life. I actually moved to another country in March and was looking at universities there when I unexpectedly got a TAship in my home country. I had only been in Awesome Foreign Country for a week when I got the offer. The University of My Home Country wouldn't give me til April 15th, saying they were pressed for time and needed my answer within a week, so I accepted on a gamble that it was the better option than staying in Awesome Foreign Country.
Now that a few months have passed I have no desire whatsoever to leave Awesome Foreign Country. I took a few classes at the local university - not exactly in my field, but a related one, and I have enjoyed them thoroughly. There's been interest from Uni of AFC in having me as a PhD student in said related field. I have the possibility of a work permit and then longer--term residency if I stick around so there are no visa issues. I've networked a lot and am starting to build some pretty solid professional relationships. And damn, I'm just really happy here.
There are many reasons that a PhD at U of MHC would be a great opportunity, but what it comes down to is I feel like I am engaged to a person from a good wholesome background that my family would approve of, but I'm just not in love and don't see myself spending the rest of my life with them. I want to call off the wedding, even though the hall has been booked and the deposits paid...know what I mean?
I hate screwing people and I'm not pleased about inconveniencing the U of MHC, especially since my TAship is pretty involved with mentoring and other such stuff. I can't really let guilt drive me though, considering that if there was an unexpected pregnancy, chronic illness or being fatally struck by a falling object the department would have to replace me...when dealing with a large number of personnel those situations are always a possibility - shit happens and if the university doesn't have a back-up plan, it's not really my problem, right?
The worst case scenario I can think of is that I would be persona non grata for life at U of MHC and I could never collaborate with that faculty because they'd just be too pissed off. But I am no longer pining exclusively for a career in academia - in my field I can make a perfectly good living without PhD working outside of university institutions so I don't think I have ruined my career possibilities.
How can I handle this with U of MHC? It sucks for them, and I want to be as professional as possible, and express my apologies, which are very sincere, about the disruption that I will cause in the short-term future. I could lie, but I hate doing that. At the same time I don't want to suck up too much - it's not personal in any way, and I feel like my reasons are justified. There's really no point in me going through the motions for a PhD I'm not really interested in doing anymore and that will not do them any favors in the future.
I'd like to know your 2 Canadian cents if you have them.
-Andi