same person for four years and he is basically a friend now

Six years doing this, four of them with the same man, and I did not intend either of those things.

We meant to keep it occasional and varied. What happened instead is that we found somebody who suited us, kept seeing him, and stopped looking. He comes for dinner now, sometimes without an evening attached. He fixed our shed. My wife texts him about her week.

The thing I want to ask about happened three weeks ago and I have been chewing on it since. The two of them had an in-joke going at my own kitchen table, about something from a night I was not at, and I felt something I have not felt in six years of this. Not the good nervous. A small cold thing, over in a minute, and entirely about a joke.

That is what has thrown me. I braced for years for jealousy about the obvious part and it genuinely never came. Then a reference I was not part of took a chunk out of my evening.

There is a second thing coming, which is that he has started seeing somebody properly. He mentioned it in the way you mention something you are testing out loud. Nobody has said anything about what that means for us and all three of us are clearly avoiding it.

So two questions for people further along. Does the jealousy relocate like that, and does it settle? And has anyone kept a long arrangement going when the third gets a partner of his own, or does that reliably end it?