Not sure id followed his reasoning... someone he can trust... Cha Haein is definitely qualified even if he has no intention in dating her. Guess is also a matter of not sharing exp with someone strong lol
Also, the phone call... was he expecting it would be Cha Haein by any chance? who else? Ju-hee maybe? Well, no other girl had more focus from the author than Cha Haein when comes to that regard, i usually take that as a sign. Of course im aware this isnt a romance story by far and it normally tends to make things complicated. But shes just so damn cute that i cant help but cheer for her lol