Why do you guy friends eventually start liking you in not a friends way?

so i need more feedback in this question of mine...why do you guy friends at some point alwyas strat likeing you as mor ehen a friend...this has happned to me before and the thing is that it sucks bec its hard foe me to truly get to love somonje in that way...ehem i have a bit of trust issues but still like its hard for me to really like somone in romantic way or wahtever but anywys...this friend...my really good friend like me...my girl friend say hes in love wiht me but i dont...i really care for him and dont wanna hurt him butwaht should oi do...im sure that if and when i turn him down he'll get wierd and resented towards me and the thing im confused bec hes so sweet and a genlteman toward sme obviously thatll change later when i turn him down but i dont know what to doooo