Ok, now is my turn to campaign for Law. And I should first apologise for not doing it earlier, but RL got in the way. So, let’s try to solve this, even if the second round it’s in its final stretch.
Trafalgar Law is a well-known character from One Piece, so I’ll skip his introduction and focus in what makes him, in my opinion, a good husbando. I’m very aware that you’re not taking into account his good characteristics because of his attitude, and I have to highlight that he went through a traumatic past which made him the way he’s today. But in essence, he’s a kind, devoted and protective person, and the proof is that he’s changing little by little and showing more this characteristics.
Protective. In order to keep those he holds dear to him away from danger, Law prefers to sacrifice himself and not involve them in his personal problems. So, he’d go in a solo mission or even focus all the attention of the enemy at him to buy you some time to escape. Also, he protects others with his attitude: he doesn’t seem to be a person who likes close relationships. He prefers not to get very involved with people around him because in the past, those near to him had a fatal end.
Devoted. Law has proven to be a loyal person towards his family and other several people, not leaving their side despite the hard circumstances and dangers.
Kindness and concern. How he shows this? Even if at first he can act reluctant, once he has engaged himself with a cause, he’ll prove this engagement till the end: he can cure children from a disease, cross the sea to rescue someone or have an argument with his allies about how a whole island and it inhabitants could be wiped out if they act in a careless way.
Love. His love is so deep that, if you result harmed in any way, he’ll feel burdened by the guilt. And he will do anything to avenge you, until he realizes that you only wanted him to live on. With a smile.
Funny side. Yes, even he has one. His amazement expression when he hears talking about ninjas or when he’s drawn into the Strawhats carefree 'pace'.