I wrote two than 2 you can already see how retarded I am
The last ending you simply keep trying to learn what happened and don't be complacent. Head to the bus stop, check belongings, ask his name first, make him elaborate when you can, keep thinking of the party, question the stranger when you can, stay, answer the phone, and then convince him there's another way. Those should be enough to get you the third ending.
If you check the downloads, you should have access to the .pdf of the ending guide if you need a little more guidance!