That actually his official 'wife' not concubine, if it was a concubine he wouldn't have been so angry. Because he was forced to marry a man, meant that any children he'd have from his other concubines wouldn't be eligible for the throne. It's only through his 'wife' that he can have legitimate heirs with and be legitimate heir himself. But his wife is a dude so
Yes true Han zhang is Jing shao official wife that's why in ch 1 ~2 that's a woman he always chose to stay is a concubine but she run away after Jing Shao has been accused as getting eyes on throne before they both reincarnated.
Lol the prince asking the concubine "have you ever hated me?" legit made me scoff like ofcourse you pea sized brain fool you legit raped him and neglected him for years and not to mention him missing his oppurtunity to become an official