Can I say...
It made me feel so bad that I stayed hours trying to understand why you joined/entered in that tribe.
What is the context?
It's the beginning of a letter...
***Neither a teacher nor a native speaker.***
I believe you should use join here.
You can enter a room, but you cannot join a room.
Joining something means that you confederate with it.
I can join the army, a clan, a tribe etc.
Try to imagine that enter means to go into something.
P.S: A confirmation by teachers/others would be nice...
Cheers!