这句话可以说成 "I will be by your side forever."。
"I will be" 意思是我会，"by your side" 意思是在你身边，"forever" 意思是永远。
这句话来源于英语中常用的爱情表达。
例句：
"I will be by your side through thick and thin." (我会在你身边陪伴你，无论喜怒哀乐)
"I will be by your side till the end of time." (我会在你身边直到永远)
"I will be by your side forever and always." (我会永远永远在你身边)