I have been trying to convince my wife for a few years now ..most she will do is roleplay fucking someone else
We roleplayed for sone years as well, using toys and dirty talk. At some point during the roleplay I would ask her to beg me to find a strangers cock for her. She did. Later I would tell her that I was indeed searching and that a lot of guys wanted to fuck her. I described just some fictional men, but she liked it..
I eventually did post an ad on an adult SPAM, found a guy with experience, positive reviews, good looks and yes, a very big cock. I met with him, to find out if there was chemestry and we talked about the situation..
I then texted with my wife (she was on vacation), asking her to book a certain date for a meeting with a guy on a hotel. She was surprised and wanted to know if it was for real, but I could tell she was turned on..We sexted, she came and we agreed to talk it through when she came home.
She had lots of reservations, questions and demands - things she would NOT do. I made no demands and let her set up the rules. She was not sure she would kiss him and she was quite sure she was not going to blow him. When we met, it did not take long before they kissed passionately and right after that she dropped to her knees and took him in her mouth...
What worked for us was baby steps, making the roleplay more realistic and detailed I think.