I [30m] booked an erotic massage for my fiance [33f] and sat in the waiting room while she was pleasured

A fun stage of a relationship is where you get to the point where you share fantasies. My fiance told me she had a fantasy of going in for a massage that turns sexual. I have a bit of this wife sharing kink so I thought this sounded incredibly hot.. I made a few Reddit posts basically saying I was seeking a massage that turns erotic, preferably at an actual legitimate massage establishment for my fiance. Besides a bunch of comments saying “no real massage therapist would provide this they will lose their license”, one massage therapist with a small private practice actually reached out said he’d be willing, but it must all be discussed and consensual, which was a green flag. My fiance was nervous but was up for it. I drove her to the place which was in a small office park building. We walk inside and meet the guy and there is some award tension. He tells me I can wait in a special waiting room he has and to make myself comfortable. There was some hinting about what we had discussed but not overly overt, but that it could go as far as she wants. He leaves for a moment and comes back to lead her to the room and the fucking guy is sporting a huge erection clearly visible through his loose yogi pants and that was humiliating already. He leads her back and I can’t explain the mix of emotions but incredible arousal I had. I didn’t know how far it would go. Eventually I sat against the thin wall and put my ear to it and could just barely make out some noise. Eventually he came to the waiting and said I could go in the massage room now, he was finished. I’ll never forget how hot it was walking in and seeing my butt ass naked fiance all oiled up and splayed out. She gave me a meek “hey” and a quick kiss. She said eventually she’d had enough of the tantric stuff and didn’t let it go any further. I asked her if she had an orgasm and she said “a little one”. She said he was “very skilled with his fingers” but eventually she was a bit uncomfortable and so had enough. Back in the waiting room the therapist said “be sure she goes to pee before leaving” for hygiene due to “genital contact”. He said he’d love to have her back. I tipped him and we drove home and she said it was only fingers and nothing more but we barely have talked about it since.