Baekhyun is your best friend, but you have a huge crush on him

The sad thing is he has a girlfriend...

When she breaks up with him he is devastated
He will do anything to get her back

Then he asks for your help to make her jealous
Seeing the chance to be with Baekhyun
You say yes

A month, 
That's the deal

But what if your feelings only get deeper?
And what if his ex wants him back at the end?