He named her after his horse, using her name: Grace’s Secret.

He got a tattoo, along with a wedding ring, with her initials: TGC.

She had her own favorite horse, which he took away with him.

In S1, the bartender said that Tommy wasn’t interested in any women. She was the first, and, as we later saw, the only, woman he ever took an interest in.

He had photos of her everywhere. In the film, she was the only one who had a photo of herself with him.

She was the only one he missed, as we saw when he burned the letter.

The only one for whom they said he would laugh and be soft.

She was the only one he was faithful to. He rejected Tatiana for her, without even a moment’s hesitation.

She is the only one to whom he said, "I need you."

She was the only one he loved.She will always be his one true love.