Gravity.

"I understand that you love him, but I don't understand why" he exclaimed angrily

" Why wouldn't I love him?" she yelled back just as fiercely,

He started pacing the small room, muttering angrily under his breath,

Her eyes following him as he did.

After a few minutes he turned to her and in a much calmer voice said,

"Because you love me"

She sucked in a deep breath, ready to deny it, when she realized, what was the point?
She had hurt him enough already, why not at the end, at least be truthful?
"You're right," she said. Her voice soft but her eyes fierce. " I do love you, but not enough"

He looked at her with a triumphant expression on his face.

"See, I told you," he said with a satisfied grin.

"But, don't you see?" she exploded "I want you, but I need him."

She took a few deep breaths and then continued.

" He's what keeps me here, he keeps me from floating away. He's my gravity"

He walked over to her, closing the gap between them.

"Who needs gravity? He said with a secretive grin.

"What do you mean, "Who needs gravity?"" she quoted sourly, suddenly very interested in the stain on the carpet.

"He lifted her chin up and tilted her face till she was looking him in the eyes.

Then very softly and very intently he whispered in her ear.

"Who needs gravity? We'll fly."