To keep it brief, I am thinking heavily about leaving my current PhD program with a MSc after 4 years to embark on a PhD in a field I am more interested in, as I have grown to dislike my current field. There are a series of problems within my group, from a completely unaware and ambivalent supervisor, to internal issues, to a general lack of quality of life due to many factors. All of that bundled with my desire to pursue my passions has left me wanting to move on to a different school.
I am, however, worried about my supervisors reaction if I ask him to do so. I know from past experience he has been pretty hostile to students who have wanted to do this, and furthermore, if he gives me a reference letter, I don't know how good it will be. I know I am a good student with good technical and research skills, but he is so absent from the group here (as he directs another group overseas, where he spends 95% of his time) that I feel that he doesn't even know what I have been doing/am proficient in.
I am wondering what your advice is in dealing with this sort of situation; do I suffer through, and leave with a PhD in a field and topic I resent? Or do I go on to do what I love, at the risk of being extradited by my supervisor, potentially leaving me unable to do so? It really is a classical dilemma, and I am genuinely worried either way.