First time sexual attraction. pls help me:(

I m a 27 yr old Muslim girl. i have a 6 year old relationship with my bf . we didn't have sex ever. first time in my life i felt sexual attraction towards a guy whom i met 6 years ago but till then i had made commitment to my bf so i could not pursue that guy. But from last 4 years i am in contact with that guy and fancy him all the time . We do not have any kind of relation but i fancy him all the time. I am deeply sexually attracted towards him. When my relation with bf started i had attraction towards him (but not sexual). NEVER in life i felt to have sex with any guy even when my bf touched me i told him that i don't feel any urge of sex. But from last 6 months,first time in my life , i have started thinking about sex and that too about my crush. I think about him all the time and i lust after him a lot. He is the perfect man hero i ever idealized. My question is , should i marry this other guy leaving my b.f? we are Muslims and i cant afford to have sex with other guy before marriage,however i can know him being friends or partnersbut cant do sex .. my bf is very nice person his nature compatibility is perfect with me but the only issue is ,when i think about sex i do nit fancy him, please tell me what should i do ?? i am under huge pressure of marriage from my bf and my family. the other guy is also showing interest towards me now.

note : i am that person who does not feel sexual attraction easily. This guy, my crush, is the only one i have gotten sexually attracted to ever in my life so that's why i m thinking to consider him for marriage, and i m afraid that if i marry my bf just out of compatibility i may have wandering eyes.

@sussiedqq thank u for response. i want to add some info. its not that i feel sexually repelled by my bf i do have a bit sexual attraction towards my bf but as compared to the other guy its too much less. means when i compare them the lust for crush is too big because he is more handsome than my bf and just like my ideal hero i always wanted, i feel that urge to do sex with that crush guy whenever i think about him. and i feel we will have great sex. but we are muslims so only option i have is to be friends with crush to know more about him and then get married to him. i cant do sex with him without marriage. My crush guy is an introvert, he seems emotionally guarded, has many flings, does occasional sex with girls, but no serious gf though. he once loved someone madly but she left and after that he has become a womaniser. But i believe that he can change after marriage (correct me if i m wrong) because he lost trust on women after his first love left him. The main issue is that i fantasise about him all the time but i am also afraid if i marry him will he continue to womanise after marriage or not? and will i forget my bf who is my best friend and emotional partner?. its been so many years and i couldnt get over this crush.my relationship with bf has totally damaged from last many years after i saw this guy because i couldnt take off my mind. If my crush proposes me should i ask him for some time know to each other more? and come up with the question of his womanising ?

also i wnt to ask how much is aesthetic need importnt for marriag? i had attrctn to my bf in start but that attrctn vanished soon after my crush who i find very very aestheticlly pleasing...he is so handsome just like how a man should be (in my eyes)... also i want to mention tht i m high aesthetic sensitivity i love to make attractive people my friends as well (not talking abt reltn only)