Why did my psychologist react badly when I said I wanted to see a psychiatrist?

Several issues. Without knowing what your problem is or what type of psychologist you're seeing, one can only speculate that the psychologist and you disagreed about the best approach to treatment. Psychiatry usually carries the implication of medication. Some psychologists are quite skeptical of the benefits of medications, at least for certain problems. Yours may have felt you were looking for an "easy out.".
Ask him/her. You would have to ask the psychologist about why they reacted that way. Keep in mind it's your choice to see whomever you would like for mental health issues be at the psychologist, psychiatrist, the social worker, etc.
Only speculation. One cannot really speculate on your individual case or even less so the reactions of your psychologist. One would hope that regardless of personal preferences or biases about medication a well-trained psychologist or any professional would not be intimidated or upset by a patient considering another specialist or opinion.