I don't think it's this one but what you described does sound a lot like a plot point in Love Crossed. SFL, a CEO suffers from a severe case of insomnia and SML (an idol) is her only non-medical cure (not scent related though, he's just soothing to her). The only difference is that she doesn't own or run the company he works at, no cohabitation, and it's a 'fuller' length drama.
Unfortunately that's all I got but I'm also super curious 'cause it does sound up my lane xD