I think it is extremely freaky when your other half thinks that you are THE ONE for him but you don't think so. Worse still if he/she (usually he) asks you to marry him. How would you answer him? It is not that you don't like/love him, it is just that you are not sure if he is the one for you. Dilemma. How difficult it is to be in love or in a relationship. What about all the promises of being together forever, how many people actually achieved that? Forever is subjective. Live life at the moment, not make promises for the unsure future.
p/s: just for the record, the abovementioned situation is not mine. i just had this sudden thought when i was listening to the radio broadcast a while ago.