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.
I thought it was someone watching their partner give/receive oral sex and cycling through anger and depressed acceptance.