Hello!
I read a bl manga long ago, I don't remember when, but here's the plot:

A rich kid who's still a high schooler wants to run away from home, he goes to an abandoned building and finds a middle aged man using his laptop.

[SPOILERS AHEAD]

He becomes obsessed with this man, the man doesn't give him his real name, gives him a nickname
They feed a cat there i think?

Later in the plot we find out the man is wanted and is in some kind of trouble trying to get back at his company for doing injustice (or something like that)

He does also develop feelings for the boy and they do run away together, stay for a night, then the man betrays him, and turns out he leaves the boy to the police so his family finds him again.

I think if anyone read it this is enough explanation 😢 sorry for any mistakes I read it long ago so obviously I only remember key scenes.
The entire manga gives off seinen vibes AND gay romance, so it's more on the heavy side rather than a cutesy / fluffy type of story

If you know the name of the manga please tell me i'm desperate 😭🙏

Is it this one? Goodbye My Accomplice

OMG YESS!! THANK YOU VERY MUCH 😭🙏🙏‼️‼️💞💞