My take on the story + symbolism
Having played Returnal before, I had quite the keen eye out for symbolism, so I kinda caught early what the story was trying to get at.
I'm a believer that the space stuff is just not real, and a lot of it is a metaphor for what is going on, as well as the broader messaging. I also think not 100% of everything needs to mean something.
So, in my view, after Arjun accidently killed Seb and Nitya left, he just started following her footsteps while also being on the run from the cops, and while doing so, he would meet people who would similarly be struck by desire for something, control, power, subservience, all while Arjun thinking he is better off than them cuz yeah he can keep it together.
Beating the bosses meant being closer to Nitya, in a sorta, this person is connected to Nitya sorta way, so he stalked them. Nitya also heard rumours of Arjun on her tail, so she was sorta rightfully terrified.
In the end, in the Yellow Shore, the desires and wants of Arjun would come up, the King being a personification of himself. Just like his dad before him, he would go and bring down "the king," apologise to Nitya, and before long turn back into the king who Nitya is subservient to. This is a trend in toxic relationships where the abuser gets a tiny moment of regret, promises better only to just go back to how it was before.
After the mental torment, Arjun just accepts Nitya doesn't want him back, and instead of promising her better just for the sake of taking her back, he lets go of his dreams of her. He apologises and finally lets her be.