the thing that makes me believe that the moleguy is actually Seju's father is also his body reaction as Seju talks badly about her mother in ch26.. (of course his dream about An Cha Hee is a nice signal.. but he showed deep emotions multiple times)
Actually I'm not into the thought Saehyun is Seju father( team Gaji really drive us to this way. But I can be wrong,too).Just my premonition say that, so I just can tell you my view:
-Maybe there was drama in the past between Saehyun and Ahn- chahee, like he was in love with her while she was in love with his father( the president)-> hopeless one-sided love.
-Saehyun's dream of Ahn- chahee: I can't say if it was his real subconscious but maybe it's because he loves her too much, we sometimes dream about our love, right?
- His deep emotions for Seju: Seju is freaking look like her mother, so I think this is one of the side. Or in the past, he promised with her mother to protect her.