We Really Shouldn't Do This

Your little step-sister is about to get married, and you've arrived at the air bnb where you'll all be staying for the week leading up to the wedding! As you arrive you bump into Fiona, who is your step-sister's best friend, and maid of honor. Fiona asks if your wife is accompanying you to the wedding, but you tell her that unfortunately she had to stay behind as she was too busy with work... Later that night, after you've all been out to dinner together, you bump into Fiona in the hallway of the air bnb. The two of you giggle and chat in the hallway until she invites you up to her room to keep talking... Upstairs, sitting together on her bed, the chemistry continues to grow. Fiona confesses that when she was younger she used to have a thing for you, and you admit that you did used to think she was cute... Somehow the two of you end up kissing; slowly and shyly at first, but with mounting urgency until Fiona is climbing onto your lap and starting to remove her shirt - but just then the two of you hear someone walking around on the landing outside the bedroom door, and you spring apart nervously! Fiona apologizes for getting carried away, saying that she knows you're married and that this can't happen, and says that you should both just forget about it and keep it together for the sake of your step-sister... A couple of days later, Fiona knocks on the door to the room where you're staying, and apologises for avoiding you. She tries to tell you that she wants things to be normal between the two of you, but you both keep moving closer and closer, unable to help yourselves, until you finally give in and start kissing again... With desperate passion, the two of you strip off as you're making out, touching each other intimately and moaning breathlessly... You gently push Fiona back on the bed and eat her pussy, as she tell you how long she's been wanting this... You make her cum with your tongue, and then she gets on top of you and desperately rides your cock until the two of you cum together and you unleash a hot load of spunk inside her! Afterwards you both feel confused and guilty, and agree to keep things above board at least until after the wedding, and then you can talk about this properly... The next day is the wedding ceremony, and of course, you both completely fail to stick to being good! You sneak away to a room together after the ceremony and make out passionately before Fiona sucks your cock, then you fuck her hard against the wall until you fill her with cum once more! At that moment you're almost interrupted by another guest but thankfully Fiona manages to send them away without them seeing you together. Days later, after you've all returned home, Fiona calls you on the phone to tell you she misses you... The two of you have phone sex before you inform her that your wife is going away on a business trip for a few days, and you'd love for her to come to your home... When Fiona arrives at your place, she feels a little shy and awkward at first, being in the home you share with your wife... But as the two of you get down to business, she starts to even find it a little dirty and sexy, being fucked on your wife's bed... You eat her pussy again, then pound her in missionary until she cums - then she begs to suck your cock, saying she wants to taste herself on you.. She sensually worships your cock with her mouth, teasing you and telling you how badly she wants to taste your cum - but just as you're getting close, you hear your wife arriving home unexpectedly!! The two of you scramble to put your clothes back on, and have to make awkward small talk with your wife, who thankfully doesn't seem to suspect anything... Weeks later, reluctantly tell Fiona that your wife is pregnant, and you've decided to do the right thing and stick by her, so you'll have to stop seeing Fiona... But Fiona has news of her own - you got her pregnant too, and she wants you to choose between her and your wife!!