So, that perfume girl is Taeha's assistant right? The one who got pushed in the lift?

Nope just a random girl. I think she was included so Haesoo can know that the perfume she smelled on Taeha isn't specifically a woman's perfume and it could just be a new perfume he started using.

Taeha is calculative in weird way, he could using this special perfurme '' unisex'' so she can misunderstanding the situation.... he want her to cling to him. He is a manipulator hope in a good way.