This is Missable.
After Milo and Lola fight, Sam will text you to say "Go to 1st and Izzard" and the Schoolyard Strangler bar.
Do that, and as you arrive, do NOT go directly up the stairs! If you go straight upstairs.. Wormhorn will be gone and you miss your opportunity!
So once you enter the bar, go straight to the right, have a chat, and she will want you to play beer pong.
Then you can go upstairs, make up with Lola, then before you leave, go right again and have that beer pong game with Wormhorn and job done!
Go to 1:31:00 on my Part 2 video to see how its done and where it unlocks.
Part 1
Part 2