You know yr gf loves you, but why you still doubt it?

I am 30, filipina, tan, asian beauty, curvy, long black hair, 5'4 in ht, i think i am gorgeous enuf. everybod says im nice, i dont like flirting at all except for my bf and i am faithful in a relt, never lie. im not really attracted to good looking guys, i am more on the personality. so i have a bf, he is english, 44. and i find him gorgeous but for him he is not he is ordinary. we are so in love with each other, and i know in his heart how much i love him. but sometimes he still cant believe that i chose him and i truly love him. just want to know, why for some other people, even though they know in their hearts that it is true why they still can't believe and sometimes they even give u a test? :(