Either way you go , your gonna feel apart.
Don't be a hypocrite and steal your best friend's girlfriend , its
not a "jun zi"
be a gentleman , let nature takes its course , don't hope for them
to break up,
but , just give him good advice on how to treat his gf well , if
the person you like , gets treated well , even when your not with
her, you will feel good inside as well.
If you take his girlfriend , you will feel guilty inside your heart
, i suggest what you can do is to get your best friend , not to do
any indecent stuff with her, but to treat her well and care for
her. After all , you came last ,
a best friend is hard to find , relationships comes and go , but
imagine the kind of mental torment he would feel if he lose his
girlfriend and HIS BEST FRIEND??
Find another girl .... don't break them apart, there's something
called karma....let nature take it's course, be it breaking up or
anything else...
Don't curse them..and good luck..