From the time of the Holy Prophet's (s.a.w.) death, Fatimah (a.s.) would be continually found with crying eyes and a burning heart.  Her sweet times in her life quickly came to an end; even though throughout her lifetime there were no real sweet periods, because there were the constant pressures, wars, and plots of the enemies against Islam and the Holy Prophet (s.a.w.).

    The hatred and grudges of Badr, Khaibar, Honain, that were hidden during the Prophet's (s.a.w.) time, now became visible.  Fatimah (a.s.) was then made the center of poisonous arrows of the enemies that came at them at every direction.
 
    Her separation of her father; the sad tormenting innocence of her husband Imam Ali (a.s.); the plots of the enemy against Islam, the worry of Fatimah for the future of the Muslims and the Qur'anic heritage, all came together severely straining her pure heart.

    Fatimah (a.s.) doesn't wish to cause Imam Ali (a.s.) greater grief by relating to him her sadness, because he already received a severe blow by these unpleasant circumstances, and misdeeds created by the people.

    For this very reason, she would go to the grave of the Holy Prophet (s.a.w.) and tell him of her grief.  And she would speak heart rendering words that would burn our inner souls: "Father dear, after you, I feel lonely.  I have remained perplexed and deprived, my mouth is inclined to silence, and my back is broken, and the wholesome water of life has become bitter to my taste." And, sometimes she would say: "The person who smells the pure soil of the grave of the Holy Prophet (s.a.w.), it is only fair that until the end of his life he should smell no other perfume.  After you, O' father, so much suffering has fallen upon me that, if they were to fall upon bright days, they would turn into dark, gloomy nights." Why does Fatimah (a.s.) shed tears in this way?
Why is she so restless?
Why is she as wild rue on fire, with no stability?
Why?!
The answer:   They must be heard from her own words.

Umm Salamah says: "When I went to see the lady of Islam Fatimah (a.s.) after the death of the Prophet (s.a.w.), and asked her how she was, in reply, these meaningful sentences were spoken by her: 'Why are you asking me how I am Umm Salamah, when I am caught in the middle of much sadness and sufferings?  On the one hand I have lost my father, the Prophet (s.a.w.), and on the other hand (I see with my own eyes that) there has been injustice done to his successor, (Ali ibn Abi Talib).  I swear to God that they have torn the curtain of his inviolability (reverence).  But I know that these are the grudges of Badr and the revenges of Uhud, that were hidden in the hearts of the hypocrites (nonbelievers).' "     Fatimah's (a.s.) life never got to completely blossom.  Her life was short just like a rose that withers away.  What kept going through Fatimah's (a.s.) mind in her deathbed:
        1- She remembered her rights that were taken away.
        2- She remembered her oppressed husband and his stolen position.
        3- She remembered him being led by his turban to the Mosque while she followed him. . .
        4- She remembered all this and a gloomy picture appeared before her tired eyes. . . then   a sigh becomes imprisoned deep in her heart. . .
        The heart which longs for the great Messenger who gave her the good news of her speedy departure after him (s.a.w.).  Oh!  How forsaken she was?!  But she was the Prophet's (s.a.w.) daughter!  She was his favorite child!  She whom the Prophet (s.a.w.) repeatedly expressed the importance of observing her rights!

    And as the Holy Prophet (s.a.w.) said: "Man is observed by respecting his children!!"
    Yet, this did not stop the arrogant ones from encroaching on her rights, nor did it stop the sinful hands from reaching out to strangle the beautiful rose before it completely blossomed!!

    Fatimah (a.s.) had now appeared pale and faint. . . only 90 days were left for her departure to Allah (SWT) and her father (s.a.w.).  On her death bed, Fatimah (a.s.) laid in calmness and tranquility; while if it was someone else in her case: they would mourn and break apart instead.

    At the time of her death she came out  clear of the faults of the people towards the injustice and oppression they received.  She blamed the people for accepting Abu Bakr's and Umar's leadership over Imam Ali (a.s.).  She foretold calamities which would take place as a result of this misdeed.

    There is a story reported that when Fatimah (a.s.) was suffering from her fatal illness, Abu Bakr and Umar came to visit her.  They asked for permission to enter, but she refused to see them.  Upon this, Abu Bakr vowed not to enter any house until he saw Fatimah (a.s.) and asked her to forgive him.  Abu Bakr, because of his oath, was forced to spend that night in the cold with no cover.

    Eventually, after Umar went and asked Imam Ali (a.s.) to enter the house and Fatimah then allowed them to enter the house keeping in mind that she obeys the commands of her husband (a.s.).  Fatimah (a.s.) shunned them, showing them her wrath towards what they have done, and waiting to reply to them on the Day of Judgment when she (a.s.) meets with Allah (SWT).
 

Source of References:
Ayatullah Makarem Shirazi.  The World's most outstanding lady.  Pages 41-43.  Tehran, Iran.
Abu-Muhammad Ordoni.  Fatima the Gracious.  Pages 245-253.  Islamic Republic of Iran.