Iseon didn't see hyundo's face tho. He only saw his back. You're reading too much into it.
Hyundo isn’t exactly a person that blends in the crowd lol.he has long hair and He’s really tall compared to the average male and it is also very apparent when he’s sitting. its just normal speculation, just like everyone else is doing in the comments.
I mean your speculation isn't making a lot of sense
Nothing so far has hinted that Iseon suspects Hyundo
Iseon is never the type to hint at anything so far in this story. He never hinted to yoomin about his true indifference or lack of excitement in their relationship. Plus it's already seen that he's observant when it comes too things related to yoomin (her likes and favorite shops, celebrities, and the bags she's made)
I don't know man. I still think you're reading too much into it. If it turns out you're right, I shall call you father ╮(￣▽￣)╭
Hyundo may not know who iseon is yet, but iseon has already seen Hyundo and yoomin eating at a restaurant together. I wonder if he makes small mentions of yoomin to feel him out.