"留你在身边" 的英文表达方法有很多种，具体可以表示为：
"Keep you by my side"，意思是让你留在我身边。
例句：
I'll do everything in my power to keep you by my side. 我会尽力让你留在我身边。
I don't want to lose you, I want to keep you by my side forever. 我不想失去你，我想永远留你在身边。
"Stay with me"，意思是让你留在我身边。
例句：
Please stay with me, I don't want to be alone. 请留在我身边，我不想一个人。
I'm so scared, please stay with me. 我很害怕，请留在我身边。
"Keep you close"，意思是让你留在我身边。
例句：
I'll always keep you close, no matter what happens. 无论发生什么事，我都会让你留在我身边。
You're the most important person in my pfe, and I want to keep you close. 你是我生命中最重要的人，我想让你留在我身边。
"Stay by my side"，意思是让你留在我身边。
例句：
I promise to always stay by your side, through thick and thin. 我保证无论发生什么事都会留在你身边。
Please stay by my side, I need you. 请留在我身边，我需要你。