Not much is available about Elizabeth I's private life. She was a Queen and her private life was that—private. Much of what is suggested about her life outside the public view is based upon rumor.
We know that Elizabeth I was imprisoned from the age of eighteen until she was twenty-five, by her suspicious half-sister, Mary. When Mary died without an heir, she named Elizabeth heir to the throne, making sure the monarchy remains in the Tudor name. Elizabeth was shrewd like her father, Henry VIII. To turn England's fortunes around, she would need her father's strong, and often times harsh, character traits.
Elizabeth was successful in promoting religious tolerance. Elizabeth, against the wishes of her advisors, resisted marriage—she was "married to her job." She was able to avoid war with the two other major powers of the time, France and Spain. She saw England's treasury replenished by Sir Francis' Drakes "unsanctioned" attacks of Spanish ships returned weighted down with gold from the New World. Elizabeth also ushered in the Elizabethan Renaissance which promoted a rebirth of interest in the arts. This is the time in which Shakespeare began his career.
Elizabeth also needed to show her father's steely resolve when she had Essex (a favorite who tried to take the throne from her) and Mary, Queen of Scot (who signed a document agreeing to the murder of Elizabeth) executed. Both situations saddened her, but were political necessities.
Rumor surrounded her private life. Elizabeth spent some time with the Queen Dowager Katherine after Henry died, when Katherine remarried, to Thomas Seymour; but rumors were reported that Katherine found them kissing or in bed together, and Elizabeth left. However, another source recounts that when Seymour would plan his stealthy visits in the early morning hours, Elizabeth would be already up and reading.
As Queen, Elizabeth would wear extravagant gowns and jewels, but as a young princess, she was careful in how she appeared. We could assume that she had no desire to draw attention to herself; she was considered illegitimate, political change was possible—it proved inevitable. Her brother Edward was too young to take the throne (so his ministers advised him), but he would die young, and a political scramble would follow. Elizabeth kept her head down and handled herself with grace.
...before 1558, she took care to dress soberly, the image of chastity and modesty.
Perhaps not private, uncertain, it is said that after Mary took the throne, Elizabeth lived in fear of her life, hearing a "credible rumor" about an order sent by Mary to have Elizabeth killed. However...
...Sir John Brydges [the] honest Lieutenant, had not acted upon it because it lacked the queen's signature…
When she was crowned Queen, Elizabeth refused marriage, having a healthy mistrust of the institution, but she did have favorites, courtiers: one was Robert Dudley. It is not clear if they were lovers; they did not marry. Another was Essex.
His name was Robert Devereux, earl of Essex...
...and while she enjoyed his company, he had his eyes on the throne. There is, again, no way to be sure of extent of their relationship.
The Queen once said she lived where everyone could see whatever she did. If she stepped out of line, it would affect the public's perception of her.
Except for rumors, there was little of Elizabeth's private life that can be reported.