You've been fucking your stepmom like she's invisible lately. Even with your thick cock buried deep in her slick cunt, pounding away while she rides you slow and tight, your eyes stay closed and distant. You finish with a grunt that sounds like relief, not pleasure, leaking cum onto the sheets as she rolls off unsatisfied.
She notices everything. The way you shield your phone when texting your girlfriend. The half-hearted thrusts when she drops to her knees to swallow your cock, gagging and drooling spit down her chin while you fist her hair, finishing quicker than usual without looking at her.
Your stepmom takes matters into her own hands and checks your phone while you're fetching something from the kitchen. She finds all the messages and confronts you. But when you defend your right to a normal relationship with someone your own age, she plays it cool. She smiles, tells you she's happy for you, that stepmommy just wants you happy. She sends you back out to fetch her some comfort food. Relieved that she's taken it so well, you trot out to get the ice cream. Unbeknownst to you, your stepmom invited your girlfriend round the following night, with a plot to end the relationship and secure her position in your life, permanently.
The following night, she seduces you for old times sake. Dressed in your favourite lingerie, she drops to her knees to suck your cock until you're rock hard, taking you deep down her throat while fingering her soaked pussy. She bends over and spreads her ass cheeks, commanding you to rim her tight hole first. Your tongue dives in, sloppy and eager, circling her asshole while she moans and pushes back against your face.
She guides your cock into her pussy for hard doggy-style fucking, your balls slapping her clit with every thrust until she cums screaming. She flips to missionary, wrapping her legs around you as your dick slides deep and rhythmic into her cunt. She pulls you up for a kiss, then whispers for you to take her ass. With lube dripping down her crack, you push into her tight asshole, slowly at first, then pounding away while she rubs her clit.
The back door creaks open. Your girlfriend stands frozen in the doorway, watching you balls-deep in your stepmom's ass, her legs over your shoulders, screaming as you stretch her wide. She watches your stepmom cum on your cock as you both orgasm. Your girlfriend screams and bolts.
By morning, she's blocked you everywhere. Your stepmom cuddles you close, your cock twitching against her thigh. Worried your girlfriend will expose your forbidden affair to everyone, your stepmom suggests you both move away together, where this irreplaceable bond between you can thrive properly, just you and her, forever.