The big question for teens who are dating or thinking about dating is what they will do sexually. The problem with masturbation is the lust factor. The problem with fornication is also the lust factor. But added to the lust is the outright disobedience factor. And added to both of those is the damage you do to another person when you use him or her to gratify your own needs.
Fornication can also create a life, with all the messy complications of a teen pregnancy.
To force us to choose between F and M is to create a false set of options. It is a way of structuring the argument to force a certain conclusion. This is the lie of the world, which wants to lead you into sin no matter which choice you make. This is where the whole issue of petting comes in. This is where the whole issue of pornography and M circles back.