This SHUNGA theme is about a love triangle relationships.
They are complicated relationship..
He is customer who is smoking a cigarette on the center.
He likes her on the right side.
She is an oiran(花魁). The meaning is here.
She likes him on the left side.
He is a young male prostitute who is on the left side..
(It is not unusual at that time)
What will happen from now?
Neya no hinagata