Wife and I used to swap regularly with a couple our age.

When my wife was pregnant, he asked her to go bareback (against the rules). She said no and he put one on.

The other lady was in the theater when the baby was born, that's how close we were. But we've drifted as a foursome since, my wife only realising about a year ago why she became distant with them. He'll have forgotten about it, and I don't think she knows. This was all three plus years ago.

The other lady and I still chat semi regularly.

This week they've bought a new spa (hot tub). She's been teasing me a bit about the spa (they had one when we first met) and I've been playing along.

She's just sent me a photo of her boobs out of the water (that he took). Never had a naked boob pic from her, always slightly covered.

To me it feels like they maybe want to pick things up again, but she's too shy (like me) to say so.

I'm after people's thoughts on how to address the 'elephant in the room' (ie the request to break the rules that was denied and he respected) both with my wife and hopefully with them, as they seem to be hinting at rekindling our fun.

TLDR: friends, he asked to break a rule, was respectful when told he couldn't. They seem to want to pick things up again after a few years. How do I address any lingering problems?