Would a therapist date the stereotype colorless, gormless pharmacist is the better question.
The healthcare relationships that I've known, the relationship seems to work best if they don't have to professionally associate with each other constantly (as in, even if they are two pharmacists, it works if they work different schedules or are in different areas even if in the same pharmacy).
Any professional pairing can work, and there is no reason that a pharmacist/therapist pair has anything intrinsically wrong with it. With enough pharmacists from the older generation marrying into marginal jobs (1099-Form strippers and W2 Executive Assistant Managers) and having it work out just fine, why wouldn't this work?