One of the saddest loves tories is that of Lancelot and Guinevere.

One of the greatest knights of the roundtable of King Arthur was Lancelot.  He was loyal, wise, strong, and kind.  But unfortunately, he fell in love with Queen Guinevere.  They tried to keep their love a secret from the king, but eventually, it became known and was a catalyst for the Round Table to fall. 

Like most romances, their love bloomed slowly.  At first, Guinevere ignored Lancelot.  But not for long and she soon succumbed to his charms and they became lovers.  

Another knight, Sir Meliagaunt grew suspicious and e confronted Sir Lancelot in the presence of the King and Queen.  

This led Lancelot to issue a challenge to Meliagaunt to dispute the charge.  But in such a contest, Sir Lancelot became the victor when he cleaved his oponent's head in half.  Sir Lancelot and Queen Guinevere's honour were restored.

But rumours continued to abound and several other knights became suspicious of Lancelot and Guinevere's romantic trysts.  Sir Agravain and Sir Modred, King Arthur's nephew gathered 12 knights and stormed

Guinevere's chamber, catching her with Lancelot in bed.  

Sir Lancelot tried to escape and fought hius way out of the castle, but guards seized Guinevere who was tried and later condemned to burn to death for her infedility.  

Upon hearing the news of his beloved's imminent execution, Sir Lancelot attempted to rescue her.  He killed several of King Arthur's knights in the process.   

Angered, King Arthur gathered a troop of men and attacked Lancelot's castle, but they failed.  

Lancelot ended his days as a hermit and Guinevere became a nun at Amesbury where she died.

Lord Alfred Tennyson immortalized the doomed lovers in a poem:

Sir Lancelot and Queen Guinevere

Like souls that balance joy and pain,

With tears and smiles from heaven again

The maiden Spring upon the plain

Came in a sunlit fall of rain.

In crystal vapor everywhere

Blue isles of heaven laugh'd between,

And far, in forest-deeps unseen,

The topmost elm-tree gather'd green

From draughts of balmy air.Sometimes the linnet piped his song;

Sometimes the throstle whistled strong;

Sometimes the sparhawk, wheel'd along,

Hush'd all the groves from fear of wrong;

By grassy capes with fuller sound

In curves the yellowing river ran,

And drooping chestnut-buds began

To spread into the perfect fan,

Above the teeming ground.

Then, in the boyhood of the year,

Sir Launcelot and Queen Guinevere

Rode thro' the coverts of the deer,

With blissful treble ringing clear.

She seem'd a part of joyous Spring;

A gown of grass-green silk she wore,

Buckled with golden clasps before;

A light-green tuft of plumes she bore

Closed in a golden ring.

Now on some twisted ivy-net,

Now by some tinkling rivulet,

In mosses mixt with violet

Her cream-white mule his pastern set;

And fleeter now she skimm'd the plains

Than she whose elfin prancer springs

By night to eery warblings,

When all the glimmering moorland rings

With jingling bridle-reins.

As she fled fast thro' sun and shade,

The happy winds upon her play'd,

Blowing the ringlet from the braid.

She look'd so lovely, as she sway'd

The rein with dainty finger-tips,

A man had given all other bliss,

And all his worldly worth for this,

To waste his whole heart in one kiss

Upon her perfect lips.