So long story short, been with DP for 2 years and known each other a bit longer (albeit not very well just through mutual friends)
We generally have a good relationship and have discussed plans for wedding in the future and kids etc.
we live together in rented house.
He has mentioned to me about a couple he was friends with a few years ago (approx 3/4 years ago, before we were together, I don't know them) and has told me stories about the strange relationship this couple had etc I didn't think anything of it. But I recently found out that he was actually sleeping with the girl!! Behind her husbands back.
It's all over now and they don't even live near us anymore, but I just can't get over how casually he talked about them as if they were just friends, all of them! But not even a whiff of anything going on between DP and the woman. I'm absolutely shocked and had no idea, didn't think he would ever keep truth from me.
How would you feel about this? I don't know whether to raise it with him or not? He doesn't know that I know, I found out through a friend who knew them those years ago.
I feel like a bit of a mug for some reason.