I had a bad experience at my first place of work. Some time has passed since that incident, so I'll try to recreate the story as closely as I can remember. I am putting this here because I was missing advice at that time to the effect that I eventually did not continue that job and I have since wondered what better actions could have remedied the situation.
At that time I shared an office with a colleague. Since the professional relationship with my colleague declined over time, we tried to formalize our work process. Part of our work was to work on mobile phones that were provided by the employer and that were commonly used by us two. To get our work done we placed the devices in an accessible location in the office and made sure at the end of each day the devices were in the stash in case the other one had to work with them next day. If we took a device home to work remotely we told the other one in advance.
One time after a company vacation a higher end model of these devices went missing. There was just an empty box left in the stash. As I alluded to before, there already were tensions in the work relationship but this diminished my remaining trust in the work environment. It's not just because I could perfectly imagine my colleague was the kind of person that would steal the device, although I was never certain. We also got another person in the office whom I had no experience with and who just started with their job and did not belong to our department so other explanations were possible.
In retrospective what bothered me most is that, although we (me, colleague, boss) dealt with that situation on a surface level as professionally as possible with no one blaming anyone, but to extra secure the stash, we had no overall strategy to reestablish a somehow productive relationship again. Instead in my impression it turned into something like "last man standing", meaning whoever would quit first would also lose face somewhat in the mentioned incident.
What would have been good strategies for the people involved to move forward? Are there actual successful means to recover a work relationship from this or similar situations? Assuming everyone involved behaved professionally after that incident, how could they avoid letting mistrust creep in further? To make it clear, I liked that job (the stuff I had to do) very much, and wanted and did eventually put my career on the work experience I've gained there.