It's not certain whether the one you have now is the one you'll be with for the rest of your life. There's even no guarantee if the one you just is the one who will love you forever. Because there's no such thing as the ideal man or woman, no such thing as the right person or the right one. It is us who can make love to last a lifetime. So if ever somebody asked you: "IS HE/SHE THE RIGHT ONE?" You can answer: "I'M NOT SURE, BUT I INTEND TO MAKE HIM/HER MY ONLY ONE."