if you think about it, without the emotional attachment involved, the happy ending is just part of the whole experience of a massage that gets you to relax all over head to toe. it's more "clearing out your pipes" than a romantic hookup. most cultures that have massage done by the opposite sex are fine with it morally, and i'd venture a guess that the only relationship ever ruined by it was one that'd have to be the definition of prudish and pretty close to over anyway.
as for being a therapist and being asked about happy endings.... really, pull the stick outta there
it's no different than being tall and being asked about basketball or being a psychic and people asking you to read their palm at a party. it comes with the territory, and there's no harm intended.