Prologue
Hermione Granger and Ron Weasley lasted exactly 1 year and 6 months from the date they kissed. Years later, Ron's sister would ask him if he regretted it. Not a single moment. Even with all the messiness and the fighting and making up and incompatibility and attempts to make it work, He was curiously content that he never had to wonder what might have been.
At the start, it was good. Sure, they bickered and argued, and when Harry wasn't around to yell at them to knock it off, they'd escalate to the point of absurdity. But the good moments (the moments they could channel all those emotions into passion) more than made up for it. They were still distracted, Hermione and Ron. That first summer was a blur of memorials, testimonies, news conferences, and of course the trip to Australia to track down her parents.
Hogwarts was where the pair discovered that they wanted to be together, and their London flat was ultimately where they discovered they shouldn't. But that trip to Australia was when Hermione and Ron discovered what they could be together. Harry was there, of course, and Ginny, in their own silencio-ed room on the other side of the tent, playing wizards chess to all hours of the night (or so Ron told himself). In their own tidy room, Hermione and Ron re-discovered each other. Not the childish, bantering people they'd been before 7th year, but the older, wiser people they'd become; irrevocably scarred emotionally and physically. He learned that when she had nightmares, she twitched and whimpered, but rarely flailed or yelled out. She learned that for weeks and weeks Ron couldn't even say Fred's name without needing to retreat somewhere quiet. And they both learned that they needed to be within each others' sight at all times or panic would overtake them. Of course, they also discovered the very compatible physical portion of their relationship. As they learned about each other's bodies and quirks, they became closer than they'd ever been.
They also learned what to ignore. She ignored when he left his towel on the floor, and he ignored her constant prattling on about history or theory or whatever.
By the time the group had restored her parents memories and returned home, Hermione was entering her final year of Hogwarts, and Ron was moving into a Grimmauld Place with Harry, ready to begin auror training. During that year, they craved one another's company, meeting in Hogsmeade on the weekends, and shuttering themselves in Grimmauld for school breaks.
After Hermione graduated, she and Ron moved into a London flat together, and Ginny moved into Grimmauld with Harry (yes, Molly sent Howlers). Hermione and Ron could floo into the ministry together each morning, and floo home together at night when Ron wasn't on assignment. And within months of living in the same flat, they learned that they shouldn't be together.
By August, all those things they'd chosen to ignore about one another started coming to a head. She'd be annoyed when he left dishes on the counter and he'd ask her to shush the incessant lecturing when the Cannons were on the wireless. Her hours at the Ministry increased, and Ron found himself taking on longer and more dangerous missions. They bickered about the time they didn't spend together, her constant studying, his trips to Quidditch matches...
When Ron was 19, he realized, deep down, that they were not compatible. They were brought together by shared trauma and war survival, but their codependency was keeping them both stagnant. So when Harry and Ginny got engaged in early September, Ron and Hermione ignored the obvious pressure from their families to do the same. The longer they refused to discuss it, the more distant they became. They saw each other for only a few moments in the morning and evening, and even then they bickered. On October 1st, as Ron struggled with his occlumency studies, Hermione began lecturing him on the importance and history of the practice for the 100th time. And that was the moment they broke.
"Bloody hell, Hermione! Maybe we could have a single conversation where you don't make me feel so damn inadequate!" And he'd stormed out to the pub.
That was the nail in the coffin in the relationship. Ron often supposed they could have muddled on, as people do, pretending they were fine as things crumbled. But he was done with waiting and hoping for contentment and so was she.
On October 2nd, 1999 (a date burned permanently into Ron's mind), Hermione packed up her belongings and moved out. Because her annoying ability to be good at everything played on every insecurity Ron had. Because if he asked her to tone it down, he was asking her to give up who she was. Ron didn't chase after her. Because he wasn't going to be the person to snuff out her spirit. She kissed his cheek and told him she loved him, and that was that.
They kept their breakup quiet and out of the papers, and over time they rebuilt something resembling a friendship; not as close as they'd once been, but the grudging acceptance that they couldn't be lovers, but they could manage a careful friendship. Of course there was no choice. At least once a month Ron, Hermione and Harry were called for a media appearance, statement or interview. So as time went on, Ron and Hermione rebuilt a semblance of what was lost and returned to bickering and arguing. Harry returned to his role as peacemaker, and all was well for the three (well, four, 'cause Ginny was always there, too).
When pressed, Ron would tell people the truth. "We were young. We were forced into traumatic situations together. And we were, simply, incompatible." What he left out was that the lie of shared grief, trauma and friendship could not maintain a long-term relationship. They loved each other, yes. They always would. But love alone was not enough to cut through who they were and who they needed to be.