What hppened during Yeo Taeju’s rut was just a a light that fueled all the other things that happened between them. He told him to wait patiently at home. On context, likely means to “just be at home so when I get there, I can fuck you all I want”. Though Taeju probably doesn’t want Euihyun to be outside most of the time with what occur with the thug (forgot his name, not that it’s worth remembering). Euihyun already been on the edge lately and really overthinks ALOT, plus it didn’t help that Taeju always tend to act rash and do not understand the change in his behavior towards Euihyun. Hence, when he finally realizes it during the ocean scene and confessed to Euihyun, he took it as some leverage because of the debt. He already misunderstood Yeo Taeju from the beginning and choosing to confess when everything falls apart for Euihyun doesn’t do good at all.
You got a point
Obviously what he did was absolutely awful. But I think they have an understanding that he was in rut and wasn't really in control of himself. I mean, that's the only explanation for them not talking about what happened in the car.