The third chapter of Edmondson's & Well's Shakespeare's Sonnets, "The Sonnets in Relation to Shakespeare's Life," is brief, and based almost wholly on speculation, but none of it is presented as fact, but as a look at all the ideas that have been floated in this regard.
E&W write that many critics see the sonnets as representing Shakespeare's life, though inconclusively. There are at least four characters in the sonnets, the 'I' of the poet (though one could probably argue for a 'we' in terms of personae), the youth of the first few poems, the rival poet, and the dark lady (or ladies). Similarly, I guess similarly, at least one poem (sonnet 145) is sometimes considered to be a poem to Shakespeare's wife, Anne Hathaway based on puns (or seeming puns) embedded in the poem. Coun ter to this are critics who have a hard time reconciling the mythical Shakespeare with the man who appears to be the poet, the man who takes a mistress, a married woman at that, a man who is is sexually attracted to men and women, and so on. This shatters the idealized notion of The Bard that many have. It's messay, but what life isn't? Other evidence, thin though it is, has Shakespeare as an old man when the poems were written in relative youth (When that time . . .) or conversely, "My name is Will (136) and so on and back and forth and blah, blah, blah. Is he or isn't he? Only his hairdresser knows for sure.
The argument continues that while poems seem to express Shakespeare's point-of-view, and that maybe some of them actually do, that need not be the case for all of them. Some speculate that the poems written to the fair youth were done as an act of patronage, though the fair youth has never been identified. E&W speculate that if Shakespeare were here, "he would probably discover meanings that he was not aware of" (24). Some speculate that the young man the the object of the dedication could be the same, but this, as with everythingh, relies on speculation and little in the way of evidence. This is pretty much the case with all attempts to identify the figures in the sonnets, relying much more on speculation, educated guessing and the like, than any solid evidence. This applies to the fair youth, the dark lady or ladies, the poet, and the rival poet(s).
What is generally not in doubt is that the sonnets are the work of a master. If he has not experienced all these feelings expressed in the sonnets, he is exquisitly capable of expressing the feelings of many, of creating the various characters not just in the sonnets but in the plays. He can think and express the thoughts of those he does not directly identify with, as in he may not be bisexual, but he can express love from a man to a man or to a woman, and do it as if he were that person. He can be Iago, Ophelia, Hamlet, and so many others. And it is this, more than who the real people may or may not be, that really make the poet one we continue to read, for more reasons than I'll ever be able to articulate.