I did fremione once but I’ll add more (again, just some random thoughts)

they get married young, but wait before having kids. After Fred almost died in the battle of hogwarts, they don’t want to waste any time.

Fred is the most supportive husband, especially in regards to hermione’s career

They never lose the sense of playfulness with each other – obviously there are times when they fight and stuff, but the playfulness never completely goes away

they have their first child – a daughter – when Fred is 30 and molly is overjoyed (she wanted them to have kids earlier, but she’s not complaining)

they don’t name their kids after anyone they know or knew

Fred is the one that does most of the cooking. Not because hermione can’t, but because it’s something he thoroughly enjoys