The open ending is perfect.
I absolutely loved how they both know who he loves and yet couldn't confront it coz he knows it'll be toxic bcs of the sadist tendencies.
I feel sorry for her but who would just "accompany" his friend when they already did that behind ur back?
Would've been interesting if there was a next but the fact that there isn't and the ending is urs to make is just wonderful for me.
Ore no Kimochi ga Wakaru ka