My wife has been seeing the same male massage therapist for years.It started when I gave her a gift certificate for her birthday. She was always properly draped and it was completely professional.
They're not supposed to get personally involved with clients any more than a doctor or psychiatrist is.
The thing is, the nature of the intimate contact between massage therapist and client can have the effect the OP describes.
The therapist is trained to maintain a professional, clinical demeanor to maintain professional boundaries in order to avoid anything personal developing. I had the most awesome massage by the most handsome guy recently.
She really seemed to enjoy the show as did both the massage therapist and I. Then, when she rolled over, she actually remained topless with just a little blue towel covering her private parts.
The next time, the towel came completely off when she laid on her stomach.I was always turned on when she would tell me how he would slide his hands under the towel to massage her bare butt.