Iruma's entire life. He lived with his parents who were nothing but abusive and neglectful towards him. From an early age, his parents made him work horrible and dangerous jobs despite him being underage for most of them. He was even forced to live in the forest by his parents and once had to run from the yakuza for something they did. They eventually took their horrible treatment towards their son to a whole new level when they made a deal with Sullivan, a literal demon from Hell, in exchange for money to sell the very soul of their son who did everything they asked him to. Sure, things turned out great for Iruma following that series-starting incident, but the horrible abuse he endured by his own family is still felt throughout the story.
There's the sad fact that Iruma literally can't say no or refuse anyone's request. Flashbacks show that he would often be taking advantage of by other people, especially his own parents.
Clara had gotten so used to people hanging around her only because of her handy creation powers, she was absolutely certain Iruma would eventually leave her too. Indeed she nearly breaks down when Iruma tries to explain that he's happy to be her friend, and not because of her powers.
Balam is a very kindhearted and gentle man, but his scary appearance makes everyone terrified of him.
Series
Ameri asks Iruma what his actual goals and ambitions are. Iruma admits he's spent so long being used by his own parents and others that he's never had the time to figure out what he wants.
Iruma's breakdown in chapter 123 is just heartbreaking to watch.
Chapter 206 has Sabro return home for a short visit. His attempt to speak to his father who's been shut inside his forge has him being told "You don't have what it takes to be the Demon King". And it's basically stated that he's told this to his son many times already. 207 shows that he might be doing this to keep Sabro safe from Baal's machinations, but whatever it is, he just can't communicate with his son.
