@landnspace, I'm not sure if the worst answers will help. If it's me, I would just reload my save before the affection is so high and work my way from there. But you can try different ways.
In my case, I had no problems when my buddy's heart was around pink level. You can see from the beginning of this video for Kou's heart. (The rest of the video contains Ruka's confession and Kou's Buddy Love ED, so avoid watching it if you haven't finished these routes yet.)
In my case, I had no problems when my buddy's heart was around pink level. You can see from the beginning of this video for Kou's heart. (The rest of the video contains Ruka's confession and Kou's Buddy Love ED, so avoid watching it if you haven't finished these routes yet.)