我爱你一辈子永远不变的英文？

I Love you everlasting for whole life
应该是这个吧

I'LL LOVE YOU FOREVER AND EVER
NOTHING CAN PART US
YOU ARE THE LOVE OF MY LIFE

My heart will go on
永恒的心--泰坦尼克号主题曲。
我想这个浪漫些吧！

I love you forever

I love you forever, and that will not change

the value of a is almost unchanged