Why does my text claim the object of Sonnets 1-126 is a woman, when eNotes claims they were written about a young man?
The answer is simply because the post-Victorian, prim, proper, prudish, unaccepting literary critic who wrote your English text probably wanted to (as so often happens) censor out anything that could be read as homosexual in the world's greatest author. People just don't want to accept that Shakespeare - though he was married - might have been attracted to men.
This, though, doesn't make him "gay". For the Elizabethans, sexuality was a fluid matrix - there was no straight, or gay: and there was likely nothing taboo about sleeping with man or woman, no matter what your gender! Shakespeare's contemporary, Christopher Marlowe, famously wrote that he loved to indulge in "tobacco and boys".
Unfortunately for such critics, there is a strong vein of homophobia running throughout Shakespeare's work, and the sonnets you refer to are indeed addressed to a young man - though the later sonnets are not (they're addresssed to a dark-skinned female). For proof, refer to Sonnet 20, and its reference to "a master-mistress", undoubtedly in possession of a "thing", and not "nothing" (Elizabethan slang for male and female genitalia).