So let's talk Jason.
Fate Jason for clarification.
Jason has so much going for him. Good health, talent, vision, education, the strongest and best allies, and the favor of THE QUEEN OF THE FUCKING GODS.
But he fucked it all up. Yes Aprodite started it by essentially mindraping Medea. But Jason has every ability to see what's wrong and help her. He has the greatest team of heros to exist on his side and the favor of Hera. He had the intelligence and education to know what was wrong with Medea, he could have helped her.
He didn't, because Medea was a useful tool and not a girl who needed help to him.
This is the core of his fault. People are important but not as important as he is. Jason has the number one priority of Jason. In the right circumstances this can be overcome and his value can shine, like in LB 5 but....
If he just set his ego aside and helped Medea who he owed a great debt.
If he just told the Argonauts about Medea and asked for help.
If he has even for a second looked at the people around him.
He could have had it all. The Argonauts left him due to Medea's actions. If he had helped her he could have had the might of the Argonauts on his side to take his kingdom back. Not just that but Circe would have helped at that point most likely.
But he didn't. His Argonauts where a means to an end first and foremost. His interlude shows this. When they tell him they don't respect him he goes off and tries to make a new crew to succeed his goal. He never tries to Talk about it.
Jason cannot see his own flaws, and Jason doesn't see other people as having any inherent value as people. That's why Jason sucks.
Also fuck Aprodite.