It sucks to slowly realize that just because you work with someone, whether they're your employees or in similar roles, doesn't mean that you're their friend. There's a job to be done, so as long as things are civil and the train moves smoothly that's all that matters. They will hang out without you, bond without you, even though you see them every day, just as often as everyone else. I never realized just how much management roles can become so lonely. 

I could be imagining the whole thing, and further perpetuating my beliefs by isolating myself. Still, at least today, that's how I feel.