Maybe this is an unpopular opinion, but I don't think Doyoon should get happiness. She pretty much is just a self-absorbed individual since she "claimed a girlfriend" to actively hurt the MC and then immediately started going after her best friend. We have seen no instances of her being nice to anybody until now by offering notes which is basically just recipricating.
Basically Jiyae deserves someone actually good and Doyoon deserves to end up alone and fix her own problems.