but i kinda get it, i have had these "huchs" so many times correctly its kinda hard to ignore lol but like,, he knows her nature by now so followed by the knowledge that shes almost NEVER home by that time of the night (night gigs) he could only assume something was off by hes time response and reply ┗( T﹏T )┛
Alsoooo he's anxious that he cant be near her at this time - not being able to reach her easily to ease his mind put him on alert 100% (not me being exactly like this)
Wait I just gained consciousness. The guard lied to Jay about Taeha wanting to see him. I don't know if Jay forgot about seeing Haesoo, but once he went up to see Taeha who hadn't actually called him, both of them realised something was wrong. Combine that with his stepmother telling him he's destined for heartache, maybe the mother knows what Taehee is planning and is actually in on it and sabotaging Taeha from reaching Haesoo.

How did he even knows? Like okay it says a “hunch” but like why hahaha ( ̄ε(# ̄)Σ