They have long mating rituals. Once they are aroused genitals come out of their face/neck and couple together.

Then they stay like that for hours, like many hours, you cannot separate them because their genitals are so deep inside their body that you’ll may kill them.

After that they part ways like nothing.

Source: I have pet snails and have watched them having sex several times. To my defense I also let them watch when I have sex.