As the title states, I am currently in a STEM PhD program at an institute in which I did not struggle academically in nor did I actually struggle to find a PhD advisor, at first. However, I actually rotated through a few labs before finding my mentor, who eventually himself left for another institute (and I did not follow). Thus, the search began anew and I've struggled to find labs with both funding and the right culture. Having done about 6 rotations in my first year, with the vast majority being headed by people at my institute with less-than-secure funding and some saying though I had the intellectual chops to do well, I did not fit in enough with their culture, I've decided that this institute was not a good fit for me overall. I'm thinking with some added experience in many different labs through the rotations, and a strong letter of recommendation from my previous mentor who recently left (and a rotation mentor who I am close with), I could use it as an opportunity to switch to a better program (one I previously applied for). Additionally, this institute would allow me to go from being a thousand miles away from my family and my fiancee to being able to live at home and be with them again, thus reducing my extraneous stress and allowing me to focus even more on science. However, my instincts would tell me that the transfer due to differences in culture and personal reasons might be looked upon negatively by the admissions committee or as some risk factor. I am not sure how to answer the question "What's to stop you from disagreeing with the culture here and abandoning our program?" I know I would not think of leaving another program if I start one, but I am unsure of how to answer the question posed with a compelling argument as to why the committee should have faith in me. What do you guys think?
Edit: By "switch", I mean re-apply anew, not transfer units/credentials. I also want to add that I have not been admitted to candidacy yet as it's only been a year. I've spoken to a few of the professors in the more prestigious institute previously in the year I applied but did not receive entry into. However, I applied to a program that only accepted a few students and was not competitive enough to get off of the waitlist, but this time, I've learned a lot about other different fields and want to apply to a different program at the same institute. I'm also wondering if there is any benefit in reaching out to some of the same professors at this institute whose work I still remained interested in after a year at my current institute.