Keats and Shakespeare Expressing Disappointment in Love

This thing just came to me this morning. I was scrolling down the 'Shakespeare' tag on my tumblr, trying my best to be patient with quotes wrongly attributed to Shakespeare. Then Keats' poem ran through my brain. Alright, just the first line of it, but I'll put all of them here anyway. It's very beautiful.

I.
You say you love; but with a voice
Chaster than a nun's, who singeth
The soft Vespers to herself
While the chime-bell ringeth -
O love me truly! 

II.
You say you love; but with a smile
Cold as sunrise in September,
As you were Saint Cupid's nun,
And kept his weeks of Ember.
O love me truly! 

III.
You say you love - but then your lips
Coral tinted teach no blisses.
More than coral in the sea -
They never pout for kisses -
O love me truly! 

IV.
You say you love; but then your hand
No soft squeeze for squeeze returneth,
It is like a statue's dead -
While mine to passion burneth -
O love me truly!

V.
O breathe a word or two of fire!
Smile, as if those words should burn be,
Squeeze as lovers should - O kiss
And in thy heart inurn me!
O love me truly!

The first, second, and fifth stanzas are my favourite, personally. But then I felt that I have read something of a similar tone, but more bitter, somewhere in my huge Shakespeare Complete Works. Then I remembered.

VII.
Fair is my love, but not so fair as fickle;
Mild as a dove, but neither true nor trusty;
Brighter than glass, and yet, as glass is, brittle;
Softer than wax, and yet, as iron, rusty:
A lily pale, with damask dye to grace her,
None fairer, nor none falser to deface her.
Her lips to mine how often hath she joined,
Between each kiss her oaths of true love swearing!
How many tales to please me hath she coined,
Dreading my love, the loss thereof still fearing!
Yet in the midst of all her pure protestings,
Her faith, her oaths, her tears, and all were jestings.
She burn'd with love, as straw with fire flameth;
She burn'd out love, as soon as straw outburneth;
She framed the love, and yet she foil'd the framing;
She bade love last, and yet she fell a-turning.
Was this a lover, or a lecher whether?
Bad in the best, though excellent in neither.

It's from The Passionate Pilgrim, widely attributed to Shakespeare, although many people also contributed to the work. I have personal experience with this poem. One of my loved ones once experienced the poet's feeling exactly, and I wrote this over and over again, just to release the disappointment I felt as well. It's one of my way to express empathy.

Well, sometimes it's fun, reading something with broken-hearted tone in it. Or perhaps I read and watch too much tragedy.