He was always ready to tell her, but something always stopped him. Another person, a phone call, her retreat from the scene. Something.
Something got in his way so often that he began to believe that he shouldn't tell her.
Instead, he tried to show her how he felt as she constantly ignored his feelings. He'd bring her coffee every morning as an offering of simple admiration.
He was always by her side as a proclamation of his love.
He thought that she didn't notice.
But she did.
She noticed every little thing that Rick Castle did. She noticed every time he touched her, every time he brought her coffee, every time he annoyingly wouldn't leave her side.
And now, as she lay bleeding beneath him, he laid it all on the line.
"I love you. I love you, Kate"
And this statement of his love was the last thing she noticed before she closed her eyes and everything went dark.