Responses
I think he didn't give her the flowers directly because he thinks he doesn't deserve to face her yet. I think he's doing his best to be better as an apology to his family. He knows he's messed up and he wants to redeem himself by being a great hero, but until he's great enough he won't go and personally apologize. Also, I'm sure that he insisted on having a half ice and half fire child because he himself felt useless and hopeless many times due to his limitations and he didn't want to have kids that would inherit the limitations of his quirk.
I know his attitude towards his family is really horrible...
But in the previous chapter, he buys a flower for his wife everyday. Even though he didn't give it to her directly. But still...
And maybe, just maybe... He married her so that his children didn't have to take the after effects of his power... Which is making their temperature go high.
I myself don't know how I feel towards him. He is a bad father, but he is a great hero too.