People i really need to know this.?

ok im from bangladesh and im 24, and i live in usa for 8 years. and i want to know is it ok for a women in our culture to cheat and get away with it? im asking it here cause india is the closest. my ex is getting married and asked me that i can be her bf and her husband wont know a thing? i mean seriously? here in usa its a huge thing but whats going in there? honesty is deeply appreciated.