You and step-mommy have been very careful. You've had a fun, sexual relationship for a while now but you've been very careful not to cross any lines. You've been engaging in mutual masturbation and watching each other cum, as anything else would be too taboo even for you!
Step-mommy has a great idea though, as long as you don't have sex then it's not that bad. And technically anal isn't sex is it? She's never done it before though but she's positive it definitely doesn't count. So as long you only fuck her in the ass, you've not taken things too far.
You're so hot for her fat ass and she shakes it and moans for you to touch her, then you fill her tight virgin asshole up until you're both a quivering mess.
