I found this question on Quora and It speaks for itself:

"How can I sue my ex-boyfriend for leaving me after getting physical?

People like him should face consequences. I told him before getting physical that i will not sleep with anyone before i am sure he marries me or actually marries me. He said he wanted marriage with me and even talked about where he would like to settle down etc. He pressured me several times and finally we became physical. Recently, his behavior changed and now after 2 weeks of ignoring my calls and messages, he admitted he doesn't want relationship with me NOW. I already told my family and said to him THERE WILL BE CONSEQUENCES.. He is refusing to even give a proper reason. I want to teach him a lesson for betraying me like this. NO body should become victims like this again from him in future."