So, it's like this
Eve exist because of Tarou's love for Ririsu and will stay awake as long as Tarou love Ririsu
But because technically Eve is is also Ririsu, and Tarou fell in love with Eve, Eve can stay awake
BUT because it aint the real first love, Eve will not go away
Which make it for us to reach here. Now why does Tarou does it this way to hurt Ririsu?
1. Tarou want to stay loyal to Eve and dont want to lose her
2. Tarou don't want to be hurt if he fell in love with Ririsu
3. By removing Ririsu from their love story, Tarou will be able to prevent hurting Ririsu
Why does Ririsu hates and love Tarou at the same time and I want to remove Eve?
1. It's not healthy for Tarou to love Eve
2. Eve is basically imaginary girlfriend that looks like Ririsu, Liking Eve is basically liking Ririsu's appearance but not Ririsu herself
3. Ririsu noticed that Tarou still actually has feeling for her but rejecting the notion
4. Ririsu cares about Ebino
5. Ririsu just want to remove her quirk of seeing hatsukoi zombie, and removing Eve might help solve the problem
6. Ririsu just want Tarou for himself but can't say it herself
7. THE IRONIC EMOTIONAL EXISTENCE OF EVE IS A HARM TO THE MENTAL OF BOTH RIRISU AND TAROU