Betraying someone’s trust. Not being loyal to someone when you are in a relationship. In Hindi it means, kisi k prati nishthavaan na hona.

It’s written in Hindi as:

किसी के प्रति निष्ठावान ना होना।
The word means disloyal, unfaithful; in particular it refers to someone who promised to be with you and then broke their promise.

You could say it means "harjai" but the two words are not exact synonyms.
“bewafa” is actually a urdu word which means “faithless” or “betrayal” .Even though the word is an urdu one, it is used with regular hindi. I may not give you the exact hindi meaning of the word,but I’ll let you know as soon as i get to know.

source: https://lyricsraag.com/