I saw your ask about Pac-Man and his parents if that’s the case who did he ruin his relationships with was it his longtime friends or the people he was with during his school Academy times 
A lot of people he was close with, new and old (including Cyli and Spiral...and even his adopted family)!
Because he becomes so obsessed with the idea that his parents are out there, he easily shoves off others and goes as far as to scold them for thinking otherwise.. I like to think he might indulge more in science and history for the sole purpose of tracking down his parents.
To summarize --even if it isn't about his parents-- Pacster can easily be viewed as rude and even spiteful at times. It isn't something to excuse, but his position as a sudden hero at such a young age wearing down on his mental health and just the general treatment he gets from others eventually gets to him. This is, of course, something he focuses on and tries to fix as his story progresses and he seeks help from people close to him.
Spoilers!! He does heal from this ideology over time and eventually learns to accept that he will never see them again. Plus, all the time he put into scientific studies doesn't entirely go to waste as he does find it pretty much up his alley (esp. considering ghost biology is part of it for whatever reason idk).
Uhh hope this makes sense sorry for rambling LOL