Light was traveling along route with a commercial airline then suddenly vanished.

On the evening of July the 19th, I was outside at approximately 10:00 PM gazing upon the southern night sky. I noticed that about three to four, what appeared to be, commercial aircraft lights. Only one of the aircraft was following a rather typical flight pattern and that is what caught the attention to that of my curiosity.
The three lights that were out of the typical flight patterns, are what I was watching. All three were at about a 30° angle from the south sky. One was traveling east and the other two were traveling west, with about a 4° gap spacing between. While watching the two lights traveling westward, the one lighted object, which was in between the other two lights, simply just vanished before my eyes. I've ruled out an iridium flare, for I am lucky to have witnessed one in the daytime years ago. I would also like to add that the lighted object that vanished, never had any flashing anti-collision lights.