A relationship graph which requires no gay relationships is called a bigraph (honest, I’m not making this up) or bipartite.
That follows because if you can two color the graph so that edges only connect different colors, you just assign male to one color and female to the other.
This means there’s a tone of mathematical identities describing this. Wikipedia has a good introduction.
If you hate billionaires but like steak, have you tried eating the rich?