She comes to him in his dreams.
Not as a sort of prophet, but on particularly hard days, especially the ones where he misses the simplicity of life in the 1940's, she appears in his dreams.
They're always dancing. It must be his subconscious making him feel guilty for not making their date, even if he was trapped in the ice and couldn't physically make it. The band always plays something slow, and she appears as vividly to him as if she was there with him, in the flesh.
They always dance for what seems like hours, yet a few minutes at the same time. His dream-self has definitely improved since the first time they danced together in his dreams, though he still manages to step on her toes every once in a while.
They talk. A lot. She always know exactly what to say, and it's not always what he wants to hear. When he wakes up, he know its was just his subconscious, but also that if she was with him now, she would say the exact same thing. They understood each other so well.
He lives for these dreams. When things seem tough, he knows he only needs to fall asleep to see her beautiful face again, so he can stare into her beautiful eyes.
He misses her. It's no secret. He missed his chance with her, because he decided that he needed to be a hero rather than take the opportunity to be with her. And he would make that choice again and again. No matter how much it hurts now.
What he has with Sharon is great, better than great. They're both happy, which is more than they both could have hoped for. She's an amazing woman, but he doesn't feel the same thrill he felt when he kissed her for the first time.
Sharon knows about the dreams. It wouldn't be fair not to tell her, considering their intimacy, but she understands. She is her niece, after all. She had grown up hearing stories about him, all from her. They both miss her, but in very different ways. And Sharon wasn't going to begrudge those dreams if they made him happy. She had known, all along, that he had once been in love with her aunt.
He had been in love with her. He still is in love with her. But their love was doomed from the start. Coming back, after 70 years of being absent, there was no way to re-insert himself into her life. Besides, she had a husband, children, she had found a way to move on from him. And he had found a way to move on from her.
Granted, being with her niece was a slightly weird situation. If you had asked him beforehand, he wouldn't have chosen to be with her niece. But he had fallen, hard, for Sharon long before he found out, and life has a funny way of working things out. Things didn't work out with her, but now he gets a second chance with Sharon.
He'll never forget her. She'd come back to haunt him from the grave if he ever even dared. But he recognises that what they had, can never be returned to.
But he will see her again.
He sees her in his dreams.