The Delacours have been farmers for generations. Fleur, despite appearances, is a down to earth person, knowing the best charms to protect potatoes, best fertilizers for pumpkins, and more. During the Triwizard Tournament, she still grew enamoured with the dashing Bill Weasley, and moved to Britain.
It was at the Burrow where the relationship grew cracks. In fact, Molly quite liked Fleur, which was something Bill had trouble with. His dreams were plagued with Fleur becoming like his mother.
When one of the Weasleys’ cows had trouble giving birth, Fleur assisted it, together with Molly. This helped solidify the bond between the two women. But seeing Fleur with her hands up to the elbows smeared in blood and other bodily liquids made Bill pale. Soon, the relationship died.
Molly insisted on hosting Fleur though. And when Harry and his friends departed on their hunt for horcruxes, Fleur went with them. She’d be damned if she let the young man who had risked his life for her sister do it alone. She wasn’t some fragile flower needing protection, after all.
During the hunt, she saw the obvious attraction and stress between Ron and Hermione, and pushed them together, even giving them detailed instructions on safety first. As for herself, as the time went on, Harry grew from cute in her eyes, to something more.