I'm sorry I do not love thee, alas I love another
It was a fairy tale. Ginerva Molly Weasley's marriage was a dream come true. Ginny married The Boy Who Lived! That was every little witches' dream. To marry The Boy Who Lived, The Harry Potter! Her mother was thrilled, her brother's were thrilled. Ginny married the unattainable, the dream, the illusion that was The Boy Who Lived, or so she thought, instead what she got was Harry Potter, Harry Potter not the I just want to snog fifth year Harry, but the I just got back from a bloody war, Harry. Harry with baggage, Harry figuring, lets settle back into that short time of happiness and marry. We can get that happiness back, they both thought, but of course, reality set in soon after their marriage, they had both changed in the two years they were apart… At first ignoring that in the excitement and planning of their wedding, but within the first year, the novelty wore off. Ginny was bored. Ginny was stuck in a marriage to her brother's best friend. She realized Harry wasn't all he was cracked up to be, rather boring actually. Essentially, nothing more then your older brother's best friend whom you snog to piss him off, discard and find your true love, But instead of going in that order, Ginny married him. Disaster of course would follow.
One day (or a year and a half into her marriage), while exiting The Leakey Cauldron, to enter muggle London, Ginny ran into an old friend, a former flame. They decided to go around to a little muggle place he knew near by to catch up. Why a muggle place rather then turning back into The Leakey Cauldron, shall never be known, but it would lead to wonderful and naughty things. Suffice to say, they ended up back at his muggle flat, shagging each others brains out.
Ginny did not tell Harry what transpired that day. Nor did she tell him the next day, or the next month, or the next year or the year after that. Ginny continued to meet up with Dean. Dean loved her, Dean was made for her, Dean was perfect for Ginny, to Ginny, Dean was fun, Dean wasn't boring old Harry Potter.
Ginny did not tell Harry. Dean did not tell Harry, though neither had much if any chance to see one another these days.
Dean did not push Ginny to divorce Harry as long as she stayed faithful to him, though she thought everyday about making that a true reality. She was scared of the after shocks. The scandal of her affair. She vowed that before the year was out she would over come those fears and she and Harry would be no more, certainly Harry would understand, they hadn't touched one another in over a year! Ginny was most terrified of breaking the news to her mother, her mother would be the hardest, with her dream come true, both Harry and Hermione as her children in law.
It may just shatter Molly Weasley, but Ginny wanted to be selfish for a good reason for once in her life, Ginny wanted to be able to go out in public with her true love, Ginny wanted to be able to spend the rest of her life with the man she really loved, the boy she had initially left for Harry, the boy she had wronged all those years before, now it was entirely behind them. Dean forgave her, now all she had to do was find her husband and get him to sign off on a few sheets of parchment. Two names signed on a pieces of parchment will end four years of suffering, three years of loving another man, six months of faithfulness, so Ginny Potter can be free of her burden that is her husband The Boy Who Lived, Ginny wants simplicity and true love now, Ginny wants and is willing to give everything up so she can have Dean Thomas for good, once the parchment is completed.
In the beginning, Ginny made the drastic mistake of thinking Harry Potter was her lover when in fact he was her brother, the odd brother who looks nothing like the rest, but is your brother in everything but blood. It only took four years of marriage and nearly three years of adultery to make her realize that HER lover Harry truly was not. In actuality, Ginerva had to have realized in those first moments in Dean's flat, that that was where she belonged. She kept going back there. She was happiest there. She was never as Happy with Harry. EVER.