Three points of light in a triangle formation.

A group of friends and myself were camping in the vicinity of Kerhonkson, NY.  While stargazing, a friend of mine (female police officer from NJ) noticed "three satellites moving together in formation".  I chuckled because I had been pointing out satellites and  "shooting stars" for most of the night because out of the eight of us camping together, half had never seen one (due to the light-pollution in Northern NJ).  That's when I turned around and was amazed to see three "stars" moving in a tight, smooth formation silently gliding across the dark sky.  Their motion was fluid and constant (like a LEO satellite) up until the end of our horizon when one of the "lights" moved out of formation.  It was not a solid object because I clearly saw stars pass between the "lights".  My friends were amazed and I was left stumped for answers.  It moved from a southwesterly direction towards the northeast.
Witness elects to remain totally anonymous.  PD