Tristan is CLEAR husband material for one reason imo. He immediately sensed the snake ass nature in the current king who I'm certain is pretending to be weak and helpless while happily letting his deranged ass mother be the villain on his behalf. The Queen Dowager did heavy lifting to make him king and relegate the legitimate heir to a cursed puppet. His sis con vibes are so damn obvious that the Queen dowager is trying to make him marry so he stops trying to fuck his sister. I wouldn't be surprised if we find out he was behind the curse so she wouldn't be able to say no once he finally tries to sleep with her.