
Idk if this would help but am an introvert and let alone loves anime and stuff. But when it comes to my lover I can't really help but sound rude so I always take my chance to like yeah go on a trip, plan what to do on the trip and hold hands out of nowhere cause I know I sounded rude and I can't say am sorry cause I sort of speak honest? That just sounds plain rude when it comes out.

I understand but this fictional relationship isn't really a 1 on 1 for your relationship, yeah? So it might work for you and your partner but it's clearly not working here as they keep arguing. Some people value actions over words, some prefer the other. Kotani is acting dismissive in general and clearly Shishikura is affected by his words so his partner needs to meet him halfway.
Enemies to lovers only the lovers bit is just on Shishikura's part while Kotani still thinks they're mortal enemies.