What is an appropriate relationship between founders? (i will not promote)

Hello everyone, I am a newbie co-founder, aka the start up I joined is my first time given that role. I am currently a PhD candidate (soon graduate) and I have never work in a company, hence I sure lack perspectives on company working environment. As the title says, I am wondering what is an appropriate relationship between founders? When I was offered the role, I thought founders should be friends, or at least people who understand each other at certain levels so they can offer support both in the job and mental aspects around it. I expect to work in a more tight knit company since in my lab, there are not much socializing going in and I thought with start up company with small number of people, that would be a given. The other founder (our company’s CEO) and I didn’t know each other beforehand, so I tried to have different types of conversation with him. During the process, I was told that I have crossed some boundaries, which I totally understand and respect. I then realized his definition of employees should be “people who works and bring results”, the company should be running like a smooth machine. I was a bit disappointed and a bit lost of motivation to continue because in my head, I am not having what I expected. I still want to work with the team since I believe in the vision. Is my expectation unrealistic? Naive? How should I navigate the dynamics? Thank you! I will not promote