Replying to The ride up

Why is it people are so damn sheepish about who they sit on the chair with?
I ride solo much of the time, and it is a singles duty to hop on the lift with doubles, and triples in order to maximize efficiency in the line.
Countless times I'll be under the impression that I will be riding with a group of people, we slide up and prep for the next chair to come. As I go for the next chair, no one follows.
They just choose to make me look like the asshole taking up the entire chair.
Why do people do this? Do they think I am going to eavesdrop on their day plan or some shit?
Also:
Being a "newschooler" I often find that I am the one who ALWAYS has to initiate conversation.
If it wasn't for me trying to break the tension by saying things like "Hey havin fun?" or "Enjoying the snow out there?" we would undoubtedly ride up in complete awkward silence.
Some fucking small talk with a stranger isn't going to kill you... I don't care if it is a short lived conversation, just a few pleasantries and we're good to go.

Thoughts? This happen to you guys?