The clinicians I've interacted with have always warned me of the possible side-effects of psychotropic medications, and said they should be notify immediately if the side-effects appear. I believe this is at least standard procedure, if not legally required?
I do have a low libido. Can't say whether or not that's due to Prozac, but regardless it hasn't negatively affected my life, probably because it was low before I met my wife. If someone enters a relationship while their libido is at one level and then during the relationship it changes considerably then I can certainly see how that could be a major challenge. That's an important thing to weigh when evaluating medication.