I am looking for any kind of manga of any genre about two people being either physically or situationally connected to each other where they are the only ones they can trust.
In terms of examples there was a shoujo ai manga I read a while back about a survival game where the two mcs were hamcuffed together and needed to work together to survive, so something similar, if not as drastic would be really appreciated.

Oh, this is an interesting one. I do t have a manga that totally fits the bill but maybe Tomodachi game or Diece?

You might like Torikago no Tsugai!