Why still single

Who am I? Lets shed some light on this..
Why am I single? I simply cannot conceive of the possibility of proposing to a girl...
Because at heart, I am unable to believe that my beloved can love another...
If she can love another, then I cannot love her...
I cannot accept the possibility that I love her and she loves another...
Maybe I am just being a coward...
But proposing to a girl is the most frightening thing...
What if she says no?
Even worse, what if she says yes???
What am I to do then?
And how do you decide whom to propose to? And when to?