Fantasies and sex addiction?

OKAY. So i have had a boyfriend now on and off for a year and a couple of months... when we had a breakup for a month he decided to try get with other girls to see what it was like.. even though he told me he didnt want to get back together for other reasons. He was unsuccsesful because.. well being truthful, i could do much better. that sounds horrible and mean but he really isnt very attractive, and nobody is really interested in him. he even tried to get with sme really fa ugly girl who was a total bitch to him. Before me he hdnt had sex for a year and a half and his 2 years older then me, im 19 now and he's 21. Now that wer together im less attracted to him and the sex isnt very exciting. i liked it before cos i loved him and trusted him completely, but now i want some fantasies and kinda wierd stuff. I'm attracted to one of my male friends and I fantisise about us doing things like being tied up and having him kiss me up and down and bite my neck. Sometimes the thought of forceful sex turns me on, but controlled sex at the same time! not rape!. i dont know what to do cos (sometimes) sex wth my boyfriend is awesome especailly wen im drunk, and he says im really awesome at everything now and i know i have alot of experience. iv had him tie me up but then it was like normal sex.. just restrained.. he cant seem to get into fantasy roles either like office secutary and stuff.. i tried it with him and it just ends up like normal sex again in the end! now i feel like im falling in love with the other guy just from fantasies alone! i want to cheat on my boyfriend for the thrill but i still love him an i cant live without him... but i wonder if thats because im addicted to sex and without him, no sex. I think sexual things all day everyday and we have it as many times as i can get him erect. He has trouble keeping up with me and im sick of being the one eager to do it all the time and him not turning me on enough for an orgasim during sex. Is this normal? im guessing not! i love sex too much and crazy sex! im also bi so i have dreams about girls and wake up turned on all the time because of that.