Hera's heart simultaneously broke for him and swelled with pride and affection as she listened to him speak. She utterly adored this brother, which she couldn't always say about the other two. Yes, she loved Zeus. Deeply, whether she liked to or not. Somehow, he always managed to get under her skin and she stayed with him, despite the way he hurt her. He challenged her. He made her feel alive, even when she was so mad she could spit acid. She loved him. But she didn't always like him. And Poseidon was...
He just rubbed her the wrong way a little too much for her to be comfortable spending much time with him.
Hades, though, was intelligent, creative, sensitive, and amusing when he didn't overthink things. Hera wanted him to have the things she thought he deserved. Which actually included the Underworld. It was a realm that demanded a certain type of attention, and Hades excelled at it. He was brilliant at what he did, though she would never overtly say so. It wouldn't do to give him a swelled head, or he might start thinking like his brother. At least in regards to ambition, since it was obvious he would not follow in Zeus' footsteps when it came to relationships.
And for that alone, Hera hugged him. But as her arms went around his shoulders, she knew that it was also because she wanted to offer him comfort. She could only do that subtly too. He was proud, as they all were, and he wouldn't want to know that his sister felt sorry for his situation. But she did. And she was going to fix it for him somehow.
The embrace lasted a little longer than it would have normally, because Hera needed the time to blink away the moisture that had gathered in her eyes. She didn't want him to know that his words had made her cry, or that she felt a little sorry for herself. So to cover for it, she gave him a little extra squeeze before letting go and leaning away from him.
“You,” she told him with sincerity, “are better than she deserves, and if she doesn't see that now, I know she will. She's going to hold the beginning against you for a little while, but you will win her over, little brother. How can you not? You are a better husband than most men would be in this situation.” Better than her own, that's for sure. “Don't worry, Hades. She will see how lucky she is. I know it.”