---Jumping off Epiphany's post-
MMQC: I think that we all withheld a lot from our parents back in the 70's but I keep coming back to EL's reaction that night, flying out of the house to go look for her daughter. Makes me think she knew something wasn't right, or that her daughter was distraught about something and was panicked for her.
IMO - this was no ordinary movie date and no ordinary argument. If this was a couple that argued, and made up, and professed their crazy love for each other - then a parent's reaction might different? Like, oh she'll go to so and so's house, call later, etc...
So I am guessing that it is very possible that EL knew that her daughter was distressed about something beforehand. Mothers have a way of knowing these things... Whatever the BF/F may have said about the argument perhaps it confirmed something she knew or suspected?
So, to echo jmoose and the others; the argument is a key piece to the puzzle. So, I guess I am wondering if you don't know directly what the argument was about, was there a rumor? I mean what did people think?
And, yes, BF/F's mother knew a lot more than anyone else. And, we only know that the BF/F said she was having a breakdown...