What am I?

I think that I shall never know
Why I am thus, and I am so.
Around me, other girls inspire
In men the rush and roar of fire,

The sweet transparency of glass,
The tenderness of April grass,
The durability of granite;
But for me- I don't know how to plan it.
The lads I've met in Cupid's deadlock
Were- shall we say?- born out of wedlock.
They broke my heart, they stilled my song,
And said they had to run along,
Explaining, so to sop my tears,
First came their parents or careers.
But ever does experience
Deny me wisdom, calm, and sense!
Though she's a fool who seeks to capture
The twenty-first fine, careless rapture,
I must go on, till ends my rope,
Who from my birth was cursed with hope.
A heart in half is chaste, archaic;
But mine resembles a mosaic-
The thing's become ridiculous!
Why am I so? Why am I thus?