
You're reading but definitely zero comprehension. Yes, there are tons of indications. First of all, Yuta was part of a brothel (Golden Pavilion) that served the Yakuza, where you can't go out even in you want to, the only way was to marry a rich man (which Yuta did). Also, it is mentioned that Yuta wasn't like this before (pretty obvious why he's turned like this, no?) besides stating that in the past he looked terrified and lifeless. What's more, he mentioned he went through hell in the past. And lastly, in the last chapter it is shown when he was at the brothel, and so it was Daekwang (the bottom twin) and let's not forget Daekwang mentioning 'how cruel they can be' regarding the Yakuza. So yeah, he obviously got raped and abused in horrible ways.
This author makes a good example of people having different outlook or reactions to certain things, that victims don’t always show same emotions to the same situations they’ve gone through.
There are some rape victims that show a meek or “weak” behavior/appearance, and there are those like Yuta that put on a tough facade to stand up for themselves.
I wonder what makes that difference in reactions towards the same trauma. I have a few ideas of why, but I don’t want to sound stupid so—feel free to share your thoughts.