That was a stupid waste of regeneration energy! Nothing is gained by you being a sentimental idiot.
All he’d wanted to do was ease some of her pain, just this once when she needed him. But she wouldn’t let him. ‘She's got ice in her heart, and a kiss on her lips and a vulnerable side she keeps well-hidden,’ indeed. The last two she most certainly did, but the first? He didn’t really think so. And he knew she had seen the hurt; he had been unable to keep it off his face. Not with her.
“It’s mine to waste, River,” he said quietly, later. “You gave it to me but it’s mine now.”
“What...?” She turned to look at him and he continued in that same soft and sorrowful tone.
“You love me. You say you trust me. But you don’t, not really.” She started to interrupt and he held one hand to her lips. “You trust me to try my best to get us out of a bad situation, you trust me to help you. But you don’t trust me with you.” He took a deep and shuddering breath as they stood there, his fingers to her lips and their eyes locked. “Ten years off my life to heal my beloved wife’s broken wrist, River.” Her eyes widened at his use of the endearment. “I can hold my breath longer than that. And since you gave it to me in Berlin, it’s my regeneration energy to use as I see fit. River...”
He choked on the last word and closed his eyes against the pain of the knowledge that after everything, she still didn’t trust him enough to show him the damage. Even the damage - not all of it was his doing, but enough - that he himself had caused. He shook his head and began to turn away from her, but she wrapped her hand around his wrist and tugged him gently to her.
River slipped her arms around the Doctor’s waist and snuggled her head under his chin, her curls tickling his nose. And just as he began to think that she was simply placating him, he felt the first sob against his chest.
And he knew.
She might not show it often. She might never show it again. But she trusted him enough to show him where the damage lay.