In India it is not the norm for people to sleep together, much less live together, before getting married. That’s a strong incentive for marriage. In the West, the old saying “Why buy the cow when you can get the milk for free?” seems to have been largely forgotten, and women wonder why their boyfriends don’t propose.
My parents are Indian (I was born here), as is my wife.
If access to sex is the driving element in getting a particular guy to commit... is that really the kind of a guy a woman would want to spend her life with?
I would say to the woman "Make a list of all the things that marriage would give him that he isn't already getting".
After she makes the list, tell her "OK, you now have a list of things you know he doesn't care about".