I think her main concern is that her going to her MIL might strain their relationship as they have one of those typical saas-bahu relations. Her MIL will outwardly ask her how do you know, who told you, etc and want names and details. I actually want her to speak though to her in -laws as well because yes it does concern someones future life. But I will definately tell her to bring up the “might ruin your reputation” bit if the marriage doesn’t work out or if they find out later on about the guy.