Replying to How to go about banging a girl without getting involed in a relationship

So heres the deal. Im in long distance relationship status with my japanese gf so we are allowed to see other people.

My older brothers gf who is retarded has a younger sister thats a little less hot but is tall and has a banging body.
I know she likes me, but i dont want to get into a relationship with her, mainly because since she is less hot than her older sister (my brothers gf), if i end up going out with her it will make me look inferior.

what do