she has two older brothers and two younger sisters. their family is one of those very traditional, old money, slytherin pureblood families. some grandparents and uncles were death eaters kind of thing, but that's obviously kept very hush now. their parents were brought together as an arranged marriage to keep their blood lines pure, so were their grandparents, etc, etc. this generation is slightly more liberal, though parental approval would be something that they all kind of strive for since the family is big on image and perceived social status.
i have general sibling ideas for two younger sisters (18-26) wherein they're both a little more liberal leaning, with the youngest being a total wild child comparatively and a handful for their parents. brothers are older (30+), and i think one is very straight-laced and kind of a mirror of their father and cares a lot about image, and the other is gay and not formally ostracized for it but it's a quiet tension at holidays from their parents where they just keep a stiff upper lip and refuse to address it.
her ex would be someone she dated later on in hogwarts and while she was doing her licensing to become a healer who ultimately her parents did not approve of, and since she's kind of a daddy's girl she listened and broke up with him and has immensely regretted it ever since. more details can be worked out there for sure.
all of these are just suggestions though and i'm incredibly flexible!