I've had four PIs, and only 1 long term.
#1 was unavailable and it was chemistry... didn't like it so much.
#2 was very nice, in charge of human embryonic stem cell core facility... but I had to quit because he didn't have time for an undergrad since there was no grad student to babysit me.
#3 was a Harvard grad with heavy accent... he was the worst person in the world and he told me to quit after my first PCR failed... WTF?
Most likely, this PI was worse than yours.
My advice is do what I did after this PI discouraged me from doing any more research AT ALL.
I went around looking for MD or MD/PhD PIs.
Totally different animals.
They're actually NICE people and not megalomaniacal psychopaths because of the whole medical schools approach which generally tends to look for quality people and trains doctors to be nice to patients.
Also they've been on admission committees and thus can give you much better advice than PhD PIs ever can.
Plus, MD/PhDs are smarter than PhDs, more than likely, because it is well known that the best US students go to medical schools/law schools or REAL graduate schools (physics, for example) and NOT biological science grad schools.
Even a Harvard PhD program in biology probably doesn't compare to any of the MSTPs in terms of admission standards.
So as you might have predicted already, my fourth PI is an MD/PhD, who is fairly young and he's just starting his own lab.
He's got a lot of time currently and he's teaching me personally (like my second PI) and giving me a lot of freedom, independence and mentorship.
He's also served on the admission committee for MSTP, went to washington university in st. louis for residency, etc...
Great success!