Hermione and Ron were the expected couple. They were the couple in which everyone knew was going to get together sooner or later. They were the couple in which friends joked around saying they wanted to be like Hermione and Ron. They were the power couple besides Harry and Ginny. It was always expected that they would get their happily ever after.
Hermione and Ron did indeed get their happy endings, just not with each other.
Hermione was naive back then to think that everything was separated in black and white. There was grey and she had found it. "Always" was not forever.