Good luck finding someone. In many states, legit therapists, with skills, are licensed. Few will risk their license for excursions outside of what's defined by the license requirements into erotic massage or more.
You might look for Massage Exchange (search the term) to see if there are any potential providers in your area - most of the forum participants aren't licensed, rather amateur. Their actual skill level in both the therapeutic, and erotic domain will likely vary wildly...
There are male ...... in resort cities like Vegas and Tahoe that will perform erotic massage - expect to pay however, no matter how attractive your wife is.
It is rare to find someone to provide this service - most are amateurs with no patience, no seduction skills, and no real massage skills - they are more eager to get off on your wife, but lack the technique to encourage a partner who is reluctant.