I'll say chapter 53 is a good example. There's a sense of anxiousness and insecurity about jo's feelings towards youngwoo that's kinda off-putting. He has expressed his thoughts on his growing jealousy many times throughout the series too and it's very much giving he's not as much as a 'good guy' he comes across in the beginning
Well, you asked for proof and I gave you an answer. But it’s clearly shown that jo’s attachment grows bigger with time and it’s looking like it’ll manifest into more negative emotions. I don’t read raws so I don’t know what happens beyond the latest chapter, this is my observation from all that’s been published
also, ive seen people on tiktok saying things like, "jo is becoming more like a red flag" ,turns out he just came on ian's face while having sx.... its kind of sad how people are just trying to find ways just to hate on jo,while being aware that tj is obviously a bad influence towards ian