I want to spend the rest of my life with you ...
I am looking for a translation but not necessary a word by word.
I mean is : Je veux terminer le restant de mes jours avec toi fits here??
Je veux passer le reste de mes jours avec toi.
You can go for "restant" instead of "reste", or "ma vie" instead of "mes jours", it doesn't change the meaning.
Of course "je veux" is sharp and imperative but so is "I want".
As the other posts say, "terminer" put an emphasis on the fact you want to be with the person when you will both die, which is not the important point here.