If breast implants are never meant to be used to please a partner, why would a very reputable plastic surgeon put them in, no questions asked?

Best to Ask. Since most plastic surgeons work hard to achieve patient satisfaction, inquiring about a patient's motivation to proceed with any operation is very important. For example, if a patient is not “internally motivated”, it is highly likely that the patient will end up dissatisfied with the outcome of the procedure. For example larger breasts do not fix relationships for any significant period of time.
Because u are adult. As a 35 year old female, most assume you are a rational reasonable adult who has been provided with information & materials to make an informed consent. Certainly you signed several documents and provided your acknowledgement to the surgeon and surgery staff to proceed with surgery. The first question most physicians ask is your chief complaint. Did you say: " unhappy partner" or "small breasts"?
Difficult question. Breast implants are placed for many many reasons. There are very few "nevers". Certainly, if that was the sole reason and the pt. Shared that with me, i would have concerns. Whether i would withold the operation would depend on a lot of other factors including more in depth questions. Without being there at the time of the consultation, it's hard to know.