Rather than blaming Kou (yes he made mistakes too) I felt that Narumi manipulated him and that touma wasn't the nice guy he pretended to be. He deliberately manipulated a vulnerable girl, took advantage for his own benefit, messed with her head (convinced her Kou had no feelings for her, that he "wasn't like kou", that the kiss meant nothing etc-), bad mouthed Kou to make himself look better, put pressure on her and made Futaba constantly feel guilty. When he realised it wasn't working and that Kou was trying to fix everything with Futaba he demanded an answer despite promising her time, kept insisting and basically forced her into a terrible relationship she wasn't ready for (which he knew because he didn't want to lose his chance. The guy even saw Kou in the crowd looking for her, refused to accept a NO as an answer because as he said he knew he only had that 1 moment yet ppl paint him as a hero.
Ppl always bring up that Kou snatched Futaba when Touma said he would do the same as Kou if Kou makes Futaba cry again and Kou only asked her what she wants for herself and Futaba decided to stop pleasing ppl. The boy just asked and in the same chapter Futaba broke up with Touma. There was no snatching or courting