不管发生什么事我都会在你的身边用英语怎么说？

No matter what happens I will be always aound/wih you.

地道点be there fore somebody
No matter what happens, I'll always be there for you.

be around 和 by your side 都可以翻译成在你身边,但be your side还有"支持,鼓励"的意思，个人觉得更地道些
no matter what happens,I will always be by your side

I will be always around you no matter what happens!

No matter what happens I will be always with you.

I will be with you no matter what happens.