Does "Breach of promise to marry " amounts to 376 ipc ?

There could be no certainity in the given context. The court's decision would depend upon the facts and circumstances of each case.

What the Supreme Court had held has been that Every Breach Of Promise To Marry Is Not 'Rape'. In the given context, the Court had observed - 

"21. In the instant case, the prosecutrix who herself was a married woman having three children, could not be said to have acted under the alleged false promise given by the appellant or under the misconception of fact while giving the consent to have s*xual relationship with the appellant. Undisputedly, she continued to have such relationship with him at least for about five years till she gave complaint in the year 2015. Even if the allegations made by her in her deposition before the court, are taken on their face value, then also to construe such allegations as ‘rape’ by the appellant, would be stretching the case too far. The prosecutrix being a married woman and the mother of three children was matured and intelligent enough to understand the significance and the consequences of the moral or immoral quality of act she was consenting to. Even otherwise, if her entire conduct during the course of such relationship with the accused, is closely seen, it appears that she had betrayed her husband and three children by having relationship with the accused, for whom she had developed liking for him. She had gone to stay with him during the subsistence of her marriage with her husband, to live a better life with the accused. Till the time she was impregnated by the accused in the year 2011, and she gave birth to a male child through the loin of the accused, she did not have any complaint against the accused of he having given false promise to marry her or having cheated her. She also visited the native place of the accused in the year 2012 and came to know that he was a married man having children also, still she continued to live with the accused at another premises without any grievance. She even obtained divorce from her husband by mutual consent in 2014, leaving her three children with her husband. It was only in the year 2015 when some disputes must have taken place between them, that she filed the present complaint. The accused in his further statement recorded under Section 313 of Cr.P.C. had stated that she had filed the complaint as he refused to fulfill her demand to pay her huge amount. Thus, having regard to the facts and circumstances of the case, it could not be said by any stretch of imagination that the prosecutrix had given her consent for the s*xual relationship with the appellant under the misconception of fact, so as to hold the appellant guilty of having committed rape within the meaning of Section 375 of IPC."

In August last year, the Supreme Court had held in its order in Mandar Deepak Pawar vs State of Maharashtra that it was not rape if a consensual physical relationship was based on a genuine promise of marriage which could not be fulfilled.

You can refer to the following judgment too

IN THE SUPREME COURT OF INDIA CRIMINAL APPELLATE JURISDICTION  CRIMINAL APPEAL NO. 1368 OF 2023   SHEIKH ARIF                                                       …APPELLANT  VERSUS   THE STATE OF MAHARASHTRA  & ANR                    …RESPONDENTS    

J U D G M E N T    ABHAY S. OKA, J.  

WHEN IT IS RAPE

Anurag Soni v. State of Chattisgarh - 2019 13 SCC 119

Pramod Suryabhan Pawar v. State of Mh - 2019 9 SCC 608

No intention to marry from the very beginning - cheating established

consent given on misconception of fact , so 375 is committed by accused who gave false promise to marry

WHEN IT IS NOT RAPE 

Dr. Dhruvaram Muralidhar Sonar v. State of Mh - 2019 18 SCC 191

Maheshwar Tigga v. State of Jharkhand - 2020 10 SCC 108

when it is not false promise right from inception, offence of rape not attracted

You are welcome for your appreciations. 

Supreme Court quashes rape case after noting woman was already married, s*x was consensual

•    In August 2022 , the Supreme Court had held in its order in Mandar Deepak Pawar vs State of Maharashtra that it was not rape if a consensual physical relationship was based on a genuine promise of marriage which could not be fulfilled. A Bench led by Justice Sanjay Kishan  Kaul had then distinguished between “a false promise of marriage and breach of a promise made in good faith but subsequently not fulfilled”. The court was dealing with an FIR in which a woman had accused a man of rape and cheating. They had previously been in a consensual relationship before falling apart.
The parties chose to have physical” relationship without marriage for a considerable period of time. For some reason, the parties fell apart. It can happen both before or after marriage,” the court had recorded in its August 2022 order while quashing the FIR. The 2022 order was fortified by a 2019 judicial view of the top court in Pramod Suryabhan Pawar vs State of Maharashtra. In this case too, the court had quashed the FIR against a man accused of rape, on the grounds that the woman was “aware that there existed obstacles in marrying the accused and still continued to engage in s*xual relations”.

•    The SC in the case of Naim Ahamed vs. State (NCT OF DELHI)  held that it would be a folly to treat each breach of promise to marry as a false promise and to prosecute a person for the offence under Section 376 of the Indian Penal Code. Each case would depend upon its proved facts before the court, the court has added. A division bench of the Supreme Court made these observations while setting aside a sentence of 10 years awarded to one Naim Ahamed.
In case of false promise, the accused right from the beginning would not have any intention to marry the prosecutrix and would have cheated or deceived the prosecutrix by giving a false promise to marry her only with a view to satisfy his lust, whereas in case of breach of promise, one cannot deny a possibility that the accused might have given a promise with all seriousness to marry her, and subsequently might have encountered certain circumstances unforeseen by him or the circumstances beyond his control, which prevented him to fulfill  his promise”, a bench of Justices Ajay Rastogi and Bela M Trivedi noted.
 Court further held that, the prosecutrix who herself was a married woman having three children, could not be said to have acted under the alleged false promise given by the accused-appellant or under the misconception of fact while giving the consent to have s*xual relationship with him. “Undisputedly, she continued to have such relationship with him at least for about five years till she gave complaint in the year 2015. Even if the allegations made by her in her deposition before the court, are taken on their face value, then also to construe such allegations as ‘rape’ by the appellant, would be stretching the case too far. The prosecutrix being a married woman and the mother of three children was matured and intelligent enough to understand the significance and the consequences of the moral or immoral quality of act she was consenting to”, the bench held in conclusion.