99/100 times if someone is waiting for marriage to have sex, they are extremely unlikely to actually attempt to research and learn from other people, or experiment and communicate with their partner to get good at it on their own. They will just assume their partner is satisfied because they aren't complaining, and go on with their day. This is not a small sample size or uncommon thing, it's not a mystery or controversial topic, if you hang around with any women that are willing to talk about sex around you, you'd know this is an extremely common complaint. If you're one of the few people that waited, and then actually cared enough about it, your partner, and had the willingness and openness to get good at it after marriage, awesome, you're in an extremely small minority.
And of course it's a learning curve, that's my whole point. It's something you get good at, just like anything else. If you're too scared and puritanical about it that you don't do it until marriage, it's highly likely it's stigmatized so much that you won't be encouraged to actually put in the effort to get skilled at it, even with your marriage partner.
