Searching for THE ONE

Once heard, "A man and a woman are each born as only half of a whole piece. That is why each of us spend our lives searching for the other half. "

My thought, "If you are lucky, you will find the other piece that matches prefectly. If it's not the right piece, you can :
1. let it go and continue searching, or
2. hold on to the one on hand while continue searching (@$#&*^%*7$$%#$%%$), or
3. hold on to the one on hand and try to mould it with love (tough luck!), or
4. hold on to the one on hand and hope to live in peace with the differences (tough luck!), or
5. hold on to the one on hand and eventually live in hell with the differences (serves you right!)".

Why is it so hard for one to unleash his/her choice that is so obviously wrong in the eyes of his/her friends or relatives? Love is blind? You don't understand him/her as much as I do? You all are just jealous? He/She will change? What will I do without him/her? What if the right one never comes?

I guess some find the prospect of loneliness more unbearable.