My wife told me one of her female friends - also married has an arrangement whereby she fucks one of her husbands friends with his permission. A wife as a FWB. She asked me if it was her would I be ok with that. My wife is in her mid 50s and still likes a good fuck. I said not really as long as I knew who it was and maybe some of the details. I asked if she had someone in mind. She said "of course not, just wondering". Now I'm wondering if she does. Anyone else have something like that?

If she's "Just wondering" she definitely does have someone in mind, she's testing the water. If you are good with it, happy days.

She does. Her gf who has that FWB def had an impact on her and she wants some other hot cock giving her an amazing hot time in bed.
But she doesn't want to upset you or hurt the relationship so she plays it off like she doesn't. Just part and parcel.

I wish my gf would have a FWB.

Not really. My ex-wife and I did share a lot of fantasies openly about other people we thought about fucking, whether they be celebrities, friends, coworkers or whoever. Sometimes we would ask each other questions such as "If I were to allow you to fuck one of our friends, who would you pick and why and what all would you do with them?" Her choice was almost always another woman. She did say once that she sometimes thinks about sucking the dick of one of my guy friends.
sometimes the question would be something more like "out of our friends, who would you like to see me fuck?"
We also both had fantasies of swinging and orgies, but we both loved it as fantasy and we both felt we didn't want to actually try it in real life. I Had fantasies of seeing her fucking and sucking other guys, but would not have wanted that to actually happen in real life.
She did want to have a girlfriend and I told her it would not bother me if she was fucking another woman. She did talk with a girl she really liked, but that girl was wanting a one on one relationship and didn't want to share someone, so that didn't work out. She did say that if she found the right girl and if she was okay with it that I could watch and join in and fuck the other girl. We both had fantasies of bringing another girl in for a threesome and that fantasy we both really did want to happen in real life, but unfortunately, we never got that opportunity while we were together.
She loved watching me flirt with other women and allowed me to have phone sex with women who were friends of mine and hers and said she would have no problem masturbating in person with other women, as long as I didn't put my dick in them, I was allowed to do anything else and I had talked with a couple of women I knew about doing that and had it set up, but the more I thought about it I decideed to not do the in person masturbation because I didn't think I would cheat and put my dick in them, but I decided not to take a chance by putting that much temptation in front of myself.
At one point, she had even told me after I had gotten the offer of a blowjob from a hot female friend of mine, that she was okay with that and I should have let her give it to me. (Ugh!!!! Too late!!! lol)
But yeah, she was never interested in hardly any men. She loved my cock and gave it plenty of attention all the time, but she wanted a girlfriend, not just a FWB girlfriend, but kind of an ongoing long term relationship with a girl. She also loved me dressed as a girl, so that was awesome.
I always had thoughts about fucking many of our female friends, but I was faithful to her and would have only fucked another woman if she was involved with us, unless if she had known and allowed it. I don't cheat, but if I have permission, then maybe with the right woman, especially if she has a girlfirend and they decide to spend some fuck time without me. lol
Even just she and I sharing the fantasies of having fuck buddies, swinging and other things were hot and gave us some really great orgasms together.