Even a child created from sex isn't necessarily 'two made one' but an entirely different (and doubly estranged) 'third.' Sex is a failure we feel compelled to reenact over and over, anticipating different results - the definition of craziness, right? Imagine coupling this sort of limitless tension with public exposure.
As much as we want to penetrate the other, throw one body inside the other, fill other bodies with cum, we'll never truly get entirely 'inside.' We never succeed. Even 'normal' sex activates a highly charged liminal zone - that impossibly frustrating space of estrangement located between radically different subjectivities - between all of us. I think a lot of my shyness stems from growing up (and continuing to struggle) in a conservative, anti-intellectual culture (capitalism) where 'conformity' ranks much higher, ideologically, than any sort of creative, experiential investigation of the world.