Hi, I get quite a lot of requests for couple work. The big but though is the guy has to be bi.
The voyeur market for escort couples is also small but if you are willing to go"a bit gay", lol, either orally or the whole hog, (and have a ladyfriend escort in the local area), you might get some business. I rather suspect this is not the answer you wanted though.
I have actually booked a male escort to join me and my boyfriend but he was useless. I picked this particular one because he had an actual picture, and not a cock shot - there is nothing worse than a cock shot for advertising unless you are looking at the gay market.