Keylime, it sure seems this way. But I don't know this type of social circle, so perhaps it's not all that unusual, i.e., lots of friends but no one to have your back.
In my stream of consciousness I wonder, did the GFs want her to go to JRs that night knowing that something bad might befall her? Or did they just not want to be around her? Or not want to do any drugs? Were they glad to see her go? Do they feel she got what she deserved?
Years ago I read Margaret Atwood's "Cat's Eye" and although the girls in the story are much younger, it illustrates how cruel youth can be.
IMO, there may be a subgroup who can backstab or is unreliable but true friends have your back. I just learned that a girl my daughter considered a friend has bullied her over a boy (who likes my daughter). This girl took another friend's cell, sent an ugly text to my daughter, and then deleted it on the cell she used. In essence, she made it seem like another girl, not her, sent the message to my daughter! I'm beyond p*ssed (and sad). Trying to be positive, her real friends feel the same.
Actually, I guess that's kind of opposite from what JR may have done. But yes, kids can be cruel. We can't really compare this to LS, obviously, because it's high school vs. college. But what if, for example, someone took LS' cell for some reason (as has been speculated here before) ... or didn't alert her to some potential danger? Or maybe someone hid her phone so she couldn't call JW, and then told JW she was with CR? IDK ...
Anyhow, I do think some of LS' friends are acting strange. Also, I'll check out "Cat's Eye" ... I read "A Handmaid's Tale" (by MA) many years ago ... very good but scary.