Answer continued from above:
His feelings for this mistress range from love to disgust to hatred. He runs the whole gamut f the love-hate spectrum in his sonnets and all the trials and tribulations one experiences when involved in a love relationship.
Reference: William Shakespeare - The Extraordinary Life of the Most Successful Writer of All Time. Andrew Gurr. Harper Collins Publishers. London. 1995, pgs. 83-85
"Out of the 154 sonnets that Shakespeare wrote, 126 seem to be written to the same person." He was a rich nobleman and the first twelve sonnets urge him to marry and have children. After the first twelve Shakespeare changes his tone to one of devotion to the young gentleman. There has been rumors as to whether his devotion was one of a physical, homosexual nature, but Shakespeare's Sonnet 20 dispels these suppositions. It emphasizes that there existed a loving relationship, but not in the physical sense.
The "dark lady" appears in the last twenty-eight sonnets. They don't follow any specific order and they address more than one subject and more than one woman. "One was written to his wife Anne Hathaway, another is about his own soul, "the center of my sinful earth", and the final two are thought to be a pun on the Elizabethan cure for sexually-transmitted disease, sweating in hot tubs." The Victorians named the mysterious woman, "the dark lady," because he described her hair and coloring as black, which was the total opposite of the woman of Shakespeare's time. The title of beauty in his day was "fair." As Shakespeare describes her, she is not fair in any way, "colour, beauty, or morality, and Shakespeare has the intense emotional pain of knowing that she becomes the young man's mistress of the young man he so admires."
It really depends on which sonnets you're talking about. The first group of sonnets are considered to be the ones written to a young man, while the second group are known as the "Dark Lady" sonnets. These are broken into sonnets 1-126 and 127-154.
Check the link below for more information. If you can be more specific about which sonnet(s) you're talking about, we could definitely give you a bit more help.