He loved her. He believed he always had. He knew he always would. But in his eagerness to have her as his own, he lost sight of what was good for her. He had forced her into his own world, had molded her into a lady of society, had brought her into the company of his stiff, disagreeable, overly proud relatives. He had cost her the people she loved and that loved her back, had tried to change her into someone she was not, because he had - deep down - believed she had not been good enough as she was, that she needed to be someone more worthy, better connected, better dowered, justbetter, to justify her ascension to his lofty status.
In chasing after society's approval, a society he did not at all care for, he had lost sight of who she was and who he had fallen in love with. And now - he shuddered to think of it - he had all but destroyed her. They could not continue in this manner, he knew that now.
He could not tell what the future might bring, whether or not there was any resolution to be had. But he knew the next step, much as it pained him. He had to choose her well being over his own, what he should have done all along.
He kissed her, then set her free.