Sleeping next to someone who isn't your partner

A few weeks ago my partner and I went to a friends house to have some drinks. There was another couple, my friend his brother and myself and partner. As the night progressed people either passed out or went to sleep. The only people awake was me my friend and my partner so we decided to watch a movie in my friends bed with me in the middle and my partner was fine with that knowing my past with my friend and that we both liked each other and cheated on our partners with each other (kissed) haha. We all fell asleep and nothing happened. I just think it's strange that my partner would let this happen? I said no to being in that position I only stayed because my partner said he would cuddle me while I watch the movie...