A/N I really wanted to put Aizen back into this fic and have him attack Gin and Byakuya, but I just couldn't seem to work out how I could have them both survive, so I've just added some hints towards it.
When Ukitake and Kyōraku had returned for Gin and Byakuya's answer, they were heartbroken to be taking their Zanpakutō back to Soul Society in order to secure their freedom. However, they weren't expecting Aizen to show up and attack. It had taken all of the Eight and Thirteenth Captains' strength to protect the now-helpless Shinigami, and they had only just managed to fight the brunet off. It was probably a good thing that he had shown up, as their newly-received injuries would only cause their cover-story for Gin and Byakuya to be more believable.
Their departure had been painful on both sides, as Byakuya had great respect and room in his heart for his old teachers, and they had loved him dearly.
With promises of visits whenever they could, the Captains left, leaving Gin and Byakuya sitting in Ichigo's room together, joy filling their hearts at the prospect of finally having lives to live their own way.
Several months had passed, and neither of them could be happier. There was no longer any threat of Aizen, as the Winter War had been fought and the rogue Shinigami caught.
They had jobs at Kurosaki Clinic, as Ichigo had convinced his dad that his two 'homeless' friends had been kicked out by their families for being gay and had no money nor anywhere to stay. Once they had accumulated enough wealth, they had rented a small apartment (with Ichigo's help, of course).
Rukia visited whenever she could, and she had even warmed up to Gin, seeing just how much of a change he had made in her brother. Byakuya wasn't as cold as he once was, didn't see everyone else as inferior to him; though he was still learning how to socialise properly, he had been getting better with his politeness.
The two were currently seated on the couch together, Byakuya reading a book while Gin watched his new TV set with intense concentration. His head was rested upon his lover's lap and he purred every now and then as long fingers ran through his silver locks.
Byakuya closed his book after carefully placing his bookmark on his page. He set it down on the coffee table next to him and looked down at Gin. Gin's eyes were open and he was watching something called 'anime'. He smiled as Gin laughed loudly at something he didn't understand. It filled him to no end with joy to know that Gin was so happy these days and the mental scars that Aizen had inflicted on him had all but vanished.
"Gin, will you come to bed with me?" Byakuya asked in a soft tone.
Gin looked up at Byakuya with a large, genuine smile on his face. He understood what Byakuya was asking of him as it was not even lunch time just yet. With a kiss to his lover's lips, he nodded.
As the two walked to their bedroom, hand-in-hand, Byakuya was sure that his new life with Gin was going to be a whole new chapter for them both. He would never forget Hisana and his love for her would never die, but with Gin at his side, he knew that he now had the strength to move on and create the life he had always wanted for himself.
Despite neither of them being able to say those three words, they both knew that the other loved them with all their heart.