Unfortunately, a lot of cisgender guys don't know what to do when there's anything to do with vaginas that isn't just inserting something easily. That's not on you, that's on them (and on things like their parents and schools not giving them decent sex ed). The truth is that even when someone doesn't have vaginismus, making intercourse or other vulvovaginal kinds of sexual activities comfortable and pleasurable for the people with those parts is outside the wheelhouse of a lot of people.
I'd also add that a lot of people have the idea that not knowing what to do with anything sexual is somehow shameful, even though it's not. We're often having to ask a lot of questions of partners, look things up, experiment and explore if we really want to have sex that's good for everybody. There's no shame in anyone not knowing things, you know?
Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has. - Margaret Mead