Y'all plz help

I remember I was reading this manhwa that I thought was super cute but I forgot the name, like the FL was involved with someone in higher power and she ends up being rejected and then her like brother kills her in the OG timeline and now that FL is here she actually talks with the brother, gets close with him comes to understand him and she's the only one that goes to his magic theory presentation thing when the rest of their family didn't and there was this scene where their third brother ( not blood related but the oldest) gets called like hyung or oppa by the FL and when her brother asks why she never calls him like that she responds "cus you're my REAL brother I'm not that close with other guy" and he's all happy but turns out the oldest heard them and he looks a little dejected (I think he actually cares about them but is super shy). Like the romance with ML is one thing but I'm more interested in the cute gradual sibling bonding being shown between these 3 but fml I forgot the name YALL PLZ HELP I WANNA READ IT SO BAD