Stepsisters Innocence

Your stepsister came to you for some advice. She doesnt have friends and nobody to talk to. Her boyfriend wants to go onto the next step, sexually. But she doesnt know what to do. The most shes ever done is takeout. If she doesnt learn how to please a penis then he will breakup with her. She just wants to touch your dick. Learn how to stroke it. But you convince her she needs to atleast know how to suck it. She's a little shy at first to try and suck on it. But she ends up doing it and swallowing your cum. It's not cheating as long as I do it with my step-brother right?