Just watched ep6. The show is misleading us. Taesan CEO might not be WYW's mother.
My theory is that Junho is her son and Junho has an immediate family with autism. Taesan CEO in the last scene of ep6 was fixing things like WYW, she might have adapted that habit from her child. That child could also be dead, thus she was looking sadly with the other mother and daughter customers. That child may be the one whose born out of wedlock. Junho could be rebelling against her mother because of her. And Junho is very fond of WYW right from the start because of her.
Notice how Junho was already careful on their first meeting. He avoided touching her without her permission. He acted that way because he knows how to interact with them. And he can tell by first glance that she has ASD because he knows someone already like her. Hence he instinctly helped her. His first sentence to her was "The doors are confusing, right?" Isn't his approach is a bit weird? It was too friendly and babylike. Also, he guided her find the office, which was uncommon for some ordinary passerby. Also in that scene, it was seen that Myungseok's office wasn't his destination. He simply helped and led the way. That's rare for their first meeting if Junho was really clueless about her.