oh gosh i have so many thoughts jumping around about those two!!

like Lilith and Eda both obviously cares about each other but i think that they would start to grow apart a little around some time before the coven try outs!!

Eda was an more talented witch then Lilith, even though she’s younger, which made Lilith a bit jealous! i also think she was already trying to hide her jealousy that their parents focused more on Eda and that Eda was good at making friends while she wasn’t, so another thing to try to bottle down might have made her a bit idk resentful? and unconsciously started to get more annoyed with Eda and started to distance herself from her by studying more so she could join the Emperors Coven and playing Grudgeby (also in an attempt to get their mothers attention!)
she obviously still loves Eda but she wouldn’t interact with her as much and things Eda did that didn’t bother her before suddenly became very annoying!!

Eda on the other hand do i think was a bit confused why Lilith just kinda suddenly distanced herself, she was probably also hurt sense her best friend sister who she always were with suddenly didn’t want to be with her anymore! she might have tried to be “more” or “less” Eda in different attempts to make Lilith want to be with her again? she might have tried to be even better at magic to make Lilith impressed or something along those lines?

and then when Raeda was a thing do i think Eda and Lilith kinda distanced from each other a bit more? like i think Eda, Raine and Lilith all interacted but i think Lilith was a bit idk hurt? jealous? that her sister started to distance herself from her to be more with her new friend (at least from Lilith perspective, from Eda’s perspective so do i think she thought she was just giving Lilith the space she seemed like she wanted while spending time with her friend and crush)

so i think Lilith liked Raine but she was also secretly bitter her sister would choose this random witch that joined the school just some days ago over her! she had also be a bit annoyed that suddenly instead of it being Lilith and Eda so was it Lilith, Eda and Raine, you know?

sorry thats very rambly and probably doesn’t make sense so TLDR: Eda and Lilith cared about each other but started to grow apart around some time before the coven try out because of Lilith bottled in jealousy and when Raine joined their duo and made it into an trio did they start to grow apart a bit more (they both still liked Raine and each other, but Lilith was still a bit jealous and bitter)