Caught in the Heat of a Triangular Encounter

Last weekend, while working from home, I had an unexpected visitor. My partner and I are in an open relationship, but things took a sudden turn when our friend Sarah stopped by unannounced, looking flustered. We ended up all three of us exploring each other in the living room, the heat between us building with every touch. It started with just some playful banter, but it quickly escalated into something much more intense. I was on my knees, feeling Sarah's hand slide down her body to find me ready and waiting. Her fingers worked their magic as I guided hers lower, slipping two digits inside her, wet and eager for us both. Then she straddled me, her heat pressing against the tip of my arousal, and it was all a blur from there. The sensations were overwhelming, my cock throbbing with every slide of flesh, our moans mingling in the air. My partner joined soon after, fingers probing Sarah as she rode me. We didn’t stop until exhaustion took over. I’m left wondering if this is normal for others, or just something unique to us three? What’s your take on such spontaneous encounters? Is it common or does it just happen in the movies?