He got cheated on by the man he truly loved he is still wounded and let's be honest everyone would be like this
But that is a toxic mindset. Why put the blame on his current partner? That's not fair to his boss.
If there is no trust, the relationship is doomed. I've seen friends irl go through this. It's the MC's mindset he needs to deal with, not expect his boss to tiptoe around him. If you go into a relationship already expecting or searching for signs of infidelity, then you aren't ready to date.
My cousin let her friends get in her head and accused her boyfriend (of 6 years) of cheating constantly. Result, he dumps her, the tragic thing is he was thinking of proposing. I, also broke up with a dude (who was treated like dirt and was cheated on multiple times) who kept thinking I was cheating and asking why would I do this to him. I was baffled cause I'm a homebody who has a hatred for everyone that I don't consider my people. He was sweet but dealing with his issue and mine vice versa wasn't healthy at all. Also, suggest therapy and taking a break to heal.
I'm debating hard on dropping this now. I looked past the weird body proportions, and the slow build, but I cannot stand cheap misunderstandings just to lengthen the plot. Idk why characters in Manwha/Manga simply can't listen and always have to run off, yet when someone is clearly gaslighting them, they believe every word. Don't get me wrong, misunderstandings in plot can be done well, but IMO this is a case of it being done poorly.