1) With permission from both of them, and with the names and any identifying details changed of course, you should really consider eventually publishing this as erotica. Your writing is amazing as are the experiences described, I think people would really dig it!!
2) "Last week she asked him out on a date. Today and tomorrow she has off from work…two precious days of personal time amid the rat race insanity. She recommends that they go out today, and she says that she wants me to come along. Lunch or dinner is the plan. But she asked him on the date, not both of us. I say that I am not comfortable going because she invited him alone. If I were him, I’d be looking forward to that alone time with her and would feel bummed if then she suddenly invited someone else along! So they make plans to go in an hour or two, and he goes back to his yacht for a while leaving us alone."
Kudos on this insight!!!! It's such a hugely important point that can really hurt the new person in a threesome situation if not recognized. Just, go you.
3) Congratulations, generally, on the love and awesomeness.