I agree with you all that the weekend social event we attend together does cut into our one on one time. I don't know what to do about that. We both really enjoy that event and don't want to miss it, and it also has facilitated OSO getting to know my husband, which is important to me. My OSO's wife just isn't cool with him being gone more than one weekend every few months. She doesn't like what we are doing now, actually, she never wanted him in a LDR, but he was having no luck finding local partners and started writing to people who were farther afield. (I never wanted a LDR either, but have always been open to cyber buddies. He was just too amazing to not meet in person, then he was amazing in person, and now here we are.) He is hoping she will relax, especially as their children get older.
We actually had some tentative plans to attend a different social event our next weekend together, and I did put the kibosh on that since I want our next time together to be just us. My goal is to up the frequency of our visits to once every two months, which would give us four weekends a year that were just us, and two at the social event we both enjoy. OSO wants this too, and is hoping his wife will accept it in time.
I am drafting a letter to my friend that lists exactly where I see problems with her behavior and specifies what my personal boundaries are with regards to her and partners of mine. If she can agree to respect my boundaries, I am willing to let this go. I do agree with you, Anneintherain, that it is pretty creepy that she offers sex when the guy has already said no. She has done this repeatedly with my husband too, even after a phone conversation I was privy too where he gently told her he really sees her as just a friend and does not want a romantic relationship with her. (Husband does not like casual sex and she knows this, if he "played" with someone sexually, he would be dating them.) I think this is how she gets guys, offers them no-strings sex and then expects them to act like boyfriends. That's her business, but it can be annoying when it starts to become my business when she's after my partners. I plan to raise this issue with her as well, as tactfully as I can.