我的心只容得下你一个你的心只容得下我一个
[wŏ de xīn zhĭ róng dé xià nĭ yī gè nĭ de xīn zhĭ róng dé xià wŏ yī gè]
'My heart can only accommodate you and yours can only accommodate me.' This is like a confession declaring exclusiveness and loyalty in the love relationship.