I’ve always liked an ancient poem:
上邪
上邪，我欲与君相知，长命无绝衰。
山无陵，江水为竭。冬雷震震，夏雨雪。
天地合，乃敢与君绝。
I’ ts means that ：
A Pledge
By heaven,
I shall love you
To the end of time!
Till mountains crumble,
Streams run dry,
Thunder rumbles in winter,
Snow falls in summer,
And the earth mingles with the sky —
Not till then will I cease to love you!
I think this ancient and beautiful Chinese poem can express what you mean.