I have an incredible idea for a movie tell me what you think?

I can't believe no one has thought of this before. Alright so get this. A guy and a girl who are friends are coming out of a bad relationship, or possibly a series of bad relationships, and are sick of the whole dating scene. But get this. They both like and want to have sex! So they see no reason why they cant just have sex together as friends without any emotional attachment whatsoever. Here's the interesting part. They start to develop feelings for each other the more they have sex and one of them decides they want the other and the other isn't sure how he/she feels about it. He/she gets freaked out cause the other has feelings for them and this is exactly what they were trying to avoid. Ultimately after a heart felt speech the other who was unsure is won over and the two enter a relationship, and possibly even get married! I don't know all the details exactly yet but this is a general outline. Please give me suggestions and comments if you have any. Thank you much appreciated. Also its set to take place in the year 2511 in an apocalyptic world where mutated spider/octopus hybrids rome the earth spewing gamma ray radiation from their tentacles, set on the complete annihilation of the human race.