For some of us at some times in our lives, having a relationship with two people is less work. It requires much more communication, better scheduling, and much more attention to your partners’ feelings … but that might be a good investment of time anyhow, and often gets overlooked.
I find that having multiple partners helps me appreciate each partner much more, for themselves – it’s easy to mix up how much you love just having a partner and being loved, with how you actually feel about that person. Poly gives you the distance and contrast to see your partners clearly, and that can be really special.
Take the time to give that information, briefly but politely. It won’t burn bridges and it’s helpful for leadership to know.