You can prosecute him for the offence of cheating and rape. He has committed the crime of rape because he made a false promise of marriage. He took your consent for sexual intercourse by a deceitful act. You have given consent to establish a physical relationship because you have faith upon him.
Section 375 of the Indian Penal Code (IPC) defines the offence of rape. As per section 375 IPC, sexual intercourse by a man with a woman without her consent will constitute the offence of rape. Where the consent is obtained by the misconception of fact, it constitutes the offence of rape.
In Deepak Gulati v. State of Haryana, (2013) 7 SCC 675, the Supreme Court holds that obtaining consent on the false promise of marriage amounts to the misconception of fact. Sexual intercourse on such misconception of fact constitutes the offence of cheating and rape.
In State of U.P. v. Naushad, (2013) 16 SCC 651, the Supreme Court decides that: In the present case, the accused had sexual intercourse with the prosecutrix by giving false assurance to the prosecutrix that he would marry her. After she got pregnant, he refused to do so. From this, it is evident that he never intended to marry her and procured her consent only for the reason of having sexual relations with her, which act of the accused falls squarely under the definition of rape as he had sexual intercourse with her consent which was consent obtained under a misconception of fact as defined under Section 90 IPC.
In Yedla Srinivasa Rao v. State of A.P. (2006) 11 SCC 615, the Supreme Court holds the accused guilty of rape because he obtained the consent of prosecutrix by the false promise of marriage.
Your boyfriend was not honest right from the beginning of relationship. He never intended to marry with you, he only wants to satisfy his lust by making false promise of marriage. Therefore, he committed the offence of rape.
Hence, you may lodge an FIR under section 376 for the offence of rape. There is no limitation period for filing of FIR for the offence punishable with imprisonment of more than three years. If the police officer refuses to file your FIR, you may proceed with the Superintendent of Police under section 154(2) of the code of criminal procedure (crpc).
A police officer cannot refuse to register the FIR because the recording of FIR is mandatory under section 154 of the crpc.