My one and only:
My only love; my only sweetheart.
“My one and only” 用来形容 “某人生命中最重要的那个人”，即 “我的唯一”。它用来表示 “此人是我唯一心爱的另一半”。短语中的 “my（我的）” 可以用其它形容词性物主代词替换。
例句
My partner is amazing! I love her so much. She is my one and only.
我爱人真是太棒了！我非常爱她。她是我的唯一。
I proposed to my girlfriend because I knew I wanted to spend the rest of my life with her. She is my one and only.
我向女友求婚是因为我知道自己想和她共度余生。她是我唯一心爱的人。
That’s so cute that you told him he was your one and only. You two make an amazing couple.
你告诉他说他是你生命中的唯一，真是太好了！你们俩是天生一对。
