Shot back at you again
I look at stubborn and confrontational as almost the same thing in this instance. For example you both have your half of the program complete and the two pieces aren't fitting together.
In my past experience with programmers (when I had multiple programmers working on a job, or someone editing a prior programmers work) it is never either of the programmers fault. They are both stubborn about the possibility they could have made a mistake, which leads to confrontation when I had to go tell both of them the other one says the problem is with their work.
And yeah I tried "I don't care what's wrong, just work together and fix it guys"
Maybe you aren't like that, but a lot of people I have dealt with were.... Always a bad apple or two in the bunch though