How do I get him to fuk me??

The other week my and my best mate got very high. Were both "straight" him more then me haha. As the night got on we started talking about sex and our secret experiences one thing led to another and he whipped out his hard piece. He dared me to suck him so I did untill he was shotting his load down the back of my throat. Now the thing is im in a relationship with a girl but ever since then ive just wanted him to pound me and I want to taste him again. What do I do??