I honestly don’t know, I tried to find any clues or hints but I couldn’t. Plus I’m not as interested in this story so I didn’t look as hard, I’m currently into remarried empress so if u need spoilers for that I got u.
https://forum.novelupdates.com/threads/pet-of-the-villainess.91581/
If u want u can look here for any info about naska tho I did look and didn’t find, go check it out in case I missed something. Plus the thread is not that long so u won’t get a lot of spoilers btw.
This I know for sure: Sasha marries the green haired guy and has a son with him, and even though the villainess doesn't end up with Sasha, I can't say she has a bad ending. The villainess was able to get out of her toxic relationships with the prince and with all the unreasonable expectations put on her by the king and her parents (and practically everyone else) and becomes the next duke/duchess in her own right, without needing to marry anyone. But she remains close friends with Sasha.
This part is purely my speculations: I believe she takes Sasha's approach to marriage--in that she chooses to only marry a man who can match her--but she never finds any man as good as she is and she's only ever had romantic feelings for Sasha, so that's why she never marries. I think, even though she didn't have a fulfilled romance ending, her ending is still a good one.
SPOILER !!
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Many people in the comment section have been asking who she ends up with, I read somewhere that she will end up with the green hair dude and have a son, as for the black haired girl I’m not as sure but Im pretty sure she will not end up with anyone because she fell for Sasha but she knew she couldn’t have her or something along those lines. I saw this in a spoiler website I’m not 100% sure everything I said is correct but from all the posts they post there, this is most likely going to happen. Idk what happens to the white hair dude, I shipped him with Sasha the most (;´༎ٹ༎`).