Melody Lewis & Steam Books 
He’s Ready and Willing – A Sexy Bisexual MMF Straight Goes Gay Erotic Short Story from Steam Books [EPUB ebook] 

Don and Natalie have been together for several months now, and still, he can’t shake off the feeling that he has never been able to fully satisfy her bed. When Don discovers that Natalie’s been reading gay erotic stories on her e-reader, he comes up with a plan… but will it work? WARNING: This 4, 319-word story is a steamy read that features hot bisexual M/M sex in front of a woman, straight goes gay action, exhibitionism, masturbation blowjobs, anal sex and analingus, and may be too much for some timid readers!