Hi
Me and my gf are in relationship since 3 years after 1 year of our relationship we have started getting physical once during the intercourse she sucked my cock we were on 69 position then she make me cum by her sucking hot lips but moreover it becomes her passion and whenever we do she used to suck more instead of getting that in her Vagina
Can stay uncle help us to resolve the same
Dear @Loverboy
You are one lucky chap 
she might be every guy's dream come true!
On a rather serious note, maybe she likes the act of blowjob more than sex itself. It might be a fantasy for her.
OR it could be that she has some sort of inhibitions regarding the act of sex? Either which way you must ask her and tell her your feelings and communicate about this issue. Find out what she is feeling. I am sure you will work things out 
Cheers
my name is kunal
and i think your girl freind is best for that...and all boys wish for the same...even some married male can not get that kind after 5 years of marriage life...please allow her if you like else say that do only for forplay then enjoy intercourse.
@Loverboy
ohhh man you are lucky!
Almost every guy want a girl like your...
As @SnapDragon44 said.. you ca tell what u feel and discuss with her.
Discuss what you want... give her what she want and ask her to give what u want...