here is their policy please have a look.
Why Does Your Ad NOT Get Approved?
You are trying to advertise websites or creatives that contain adult/racy material. Our users do not want to see overly sexy images in advertisements or landing pages, and we want to keep things as clean as possible!
You are trying to advertise a FREE dating website. PlentyOfFish does not advertise these websites under any circumstances.
What do you say about it?