My partner V (29M) and I (28M) have been together for 1y8m, and been open for the last year. This is my first OR and his 2nd. It's had its bumpy moments but we always talked it out and respected one another's feelings and comfort zones. We tell each other before any planned hookup, while maintaining an allowance for spontaneous fun to take place organically. The one rule is that we don't have sex with mutual friends, to avoid complicating the vibe in our group.

I told my partner V that I was going to take our friend R to a nude gay beach. There's a bit of attraction between us (which V knows and is okay with as long as I respect the boundary). I asked V if it was ok with him if I am nude at the nude beach, in front of our friend R and he said he's fine with it as long as R is. V trusts me and is casual in his attitude about sex (with strangers/FWBs, not friends - that's a red line). I didn't end up getting nude, but I had it in my mind that I'm allowed to get nude.

Fast forward, the two of us are leaving the beach, walking through the forested path where cruising takes place. I decide to join a couple messing around with R in the background but not participating. In the moment, I think of the allowance V and I have for spontaneous fun, along with his consent for me to be nude in front of R, and the fact that I'm not doing anything directly with R. This .... was really the wrong way to think about it. V took it as crossing his boundary, and now I feel so embarrassed and guilty for not realizing in the moment that he would see it this way.

In the moment I didn't see it as a sexual act between me and our friend R, since he wasn't participating (totally clothed). It felt more like a bro-y vibe where I looked at him laughing at the spontaneity and absurdity of it. He laughed too in surprise.. but it wasn't like we were sharing sexual glances.

I made a spontaneous impulsive decision based on something I had partially thought through and I own this mistake completely. My partner was really hurt, which is the last thing I wanted to do. To be honest, I actually thought in the moment that - while yes it's a gray zone, and undiscussed scenario - I thought that he would laugh about it. I was wrong and I feel terrible. This is the healthiest and best relationship I've ever been in and I seriously see a future with V, and so does he. We talked it out, I took responsibility and apologized profusely, explained my flawed way of looking at the situation in that impulsive moment. While he was shocked at the fact that I didn't see it as crossing his line, he said he understood where I was coming from...

It's been two days and there's still stress in the air for both of us.... I have tears in my eyes... I feel nauseous and anxious knowing I hurt his feelings. He said he knows I didn't mean to hurt him, hugged me and has told me he loves me multiple times... His feelings and boundaries are important to me... I am being very hard on myself for making this mistake, even though I know we all make mistakes, and being in an OR is sometimes confusing.

Has anyone else ever done something in a sort of "gray zone" and inadvertently hurt their partner? Were you able to work through it? Did feelings eventually settle down and things get better?

Any encouragement or experiences would be appreciated. I appreciate you all.

TLDR: Got blown by two daddies (acceptable) in front of a mutual friend, at a nude beach where partner had given permission for me to be nude in front of mutual friend. Partner wasn't there. Partner considered the sex act as an off-limits sexual interaction with friend, which I stupidly didn't consider at the time. I feel terrible and stupid for my mistake. We're recovering.