Wife wants to fly solo

My wife always knew of my fantasy of letting her have sex with another man and I would encourage her to do it especially on one of her infrequent work trips. For the longest time she flippantly dismissed my suggestion. Then out of the blue, she calls me one night while she is on a trip and asks me if I was serious. She had an opportunity and asked for permission. I gave it. She had a great time. Once she accepted that she had permission and I was not going to be upset, she plays once in a while, but only on her trips. So I guess you could say that she is always flying solo. I enjoy the stories she shares with me when she returns home. But it is starting to bother me that I don't actually have any proof that she has done anything. There are never any outward marks or physical changes. She has obviously showered changed clothes before I get to see her again. I would love to see her just after she has been with a lover.

Started the lifestyle when we just turned 40 and the nest was empty. The wife was sort of hesitant at first, then when she agreed to, she said that at the beginning she'd have to do it solo.
Arranged an all-night meeting at a motel, I stayed in the room next door, just in case. She was very subdued afterwards as she said that she had to think about it and later announced to me that she wanted to do a repeat performance the coming weekend, told me that she felt safe now and I could stay home.
That Monday we sat down, and she gave me the talk.
She enjoyed this much more than she thought she would.
Could I understand that it meant a lot to her that she keeps the experience to herself, at least for a while, as we had been married since we were 18 and she never had something for herself.
Funny I felt hurt, but found that I had a much happier spouse.

I don't have to be with her every time she has sex with other men I trust her enough and it not like she's cheating and I have watched her fucking other guys plenty of times . Not all men are into being watched and and can't satisfy my wife the right way. It's not really a big deal It's just sex and when she does bring someone home It's a treat for me.

I enjoy watching my wife being pleasured by another man. We talked about our limits and one of them was to never play alone. My wife has also said she enjoys watching me with another lady. It also is for safety concerns, so everyone is comfortable. We have turned down other partners that wanted us to play separately.

During the pandemic, we swapped with our neighbor, our back yards connect and they have an in ground pool with a privacy fence.
They're older and invited us over to a cookout. It was just us and after a few joints along with alcohol, they told us they were swingers. The other couple's lived out of town and couldn't make it for the weekend. After some conversation, we agreed. His wife came home with me and my wife stayed. Once the pandemic was over, we swapped with a few of their friends. There was one older guy that was a unicorn. His wife passed away from cancer and he never remarried. He was into my wife so I agreed for her to go solo with him.

My husband and I are mid 30s and started swinging four years ago. It just happened with a group of my co-workers. From the beginning, we agreed to do this together and most couples were our age up to 50s. Plus, we connect well with similar interests.
We joined a new group but there was one older couple, mid 60s, and my husband refused to swap with because of Clara.
Bill is tall, fit, attractive and his wife Clara is bottle blonde, fake boobs, leather tan and wears lots of makeup. We didn't know how to break it to them but Bill messaged saying it was ok to play alone if I was. My husband agreed.