Okay, from the story so far Hiro father Akira was hard working, he was home late at night and Hiro had only connection with his mother.
After Akemi died, Hiro was basically left out alone and Akira remarried, his stepmom was more involved in relationship with Akira rather than also with Hiro, hardly cooked even so Hiro still felt detached from new family and after graduation left the house.
Ayame found Hiro mother Akemi cooking book and finally learned how to cook, which naturally also helped her be closer to Aoi obviously.
Guess that spirit of Akemi resting in her cooking book made her reconnect with people after she died, Hiro seems to accept Ayame as he allowed her to keep the book so she can add her own recipes to it while raising Aoi, passing down the torch.
Personally wouldn't find Ayame fully redeeming, marrying and accepting the child from previous marriage is as much important as the person you married, thought she changed for the better.
Guess it's time for the Akira to ask for forgiveness as he neglected Hiro during his childhood and after Akemi died, work is important but also family.
Thanks for the scanlation!